Journal articles on the topic 'Marsupials Reproduction'
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1
Renfree, Marilyn B. "Society for Reproductive Biology Founders' Lecture 2006 Life in the pouch: womb with a view." Reproduction, Fertility and Development 18, no. 7 (2006): 721. http://dx.doi.org/10.1071/rd06072.
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Marsupials give birth to an undeveloped altricial young after a relatively short gestation period, but have a long and sophisticated lactation with the young usually developing in a pouch. Their viviparous mode of reproduction trades placentation for lactation, exchanging the umbilical cord for the teat. The special adaptations that marsupials have developed provide us with unique insights into the evolution of all mammalian reproduction. Marsupials hold many mammalian reproductive ‘records’, for example they have the shortest known gestation but the longest embryonic diapause, the smallest neonate but the longest sperm. They have contributed to our knowledge of many mammalian reproductive events including embryonic diapause and development, birth behaviour, sex determination, sexual differentiation, lactation and seasonal breeding. Because marsupials have been genetically isolated from eutherian mammals for over 125 million years, sequencing of the genome of two marsupial species has made comparative genomic biology an exciting and important new area of investigation. This review will show how the study of marsupials has widened our understanding of mammalian reproduction and development, highlighting some mechanisms that are so fundamental that they are shared by all today’s marsupial and eutherian mammals.
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Cockburn, A. "Sex-Ratio Variation in Marsupials." Australian Journal of Zoology 37, no. 3 (1989): 467. http://dx.doi.org/10.1071/zo9890467.
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Many marsupials produce sex ratios biased towards male or female young. In several cases these changes are comfortably accommodated in the existing theory of sex allocation. Local resource competition and the Trivers-Willard hypothesis have been usefully applied to several data sets, and preliminary experimental work has supported the main tenets of theory. By contrast, several data sets lack explanation, and provide challenges to theoreticians. The high frequency of bias in marsupials does not result from data-dredging, as bias is usually reported in descriptive accounts of marsupial reproduction, without recourse to any theoretical or mechanistic explanations. It is not possible to distinguish whether the marsupial mode of reproduction is well suited to manipulate sex allocation, or whether it facilitates measurement of biased sex allocation. As for most eutherians and birds, the mechanism of prenatal sex allocation is unknown for any marsupial. However, the current interest in sex-determining mechanisms in marsupials suggests a profitable avenue for collaboration between geneticists, physiologists and evolutionary ecologists.
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McKenzie, LM, and DW Cooper. "Low MHC class II variability in a marsupial." Reproduction, Fertility and Development 6, no. 6 (1994): 721. http://dx.doi.org/10.1071/rd9940721.
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The major histocompatibility complex (MHC) loci have been shown to be highly polymorphic in most eutherian ('placental') species studied. Several hypotheses have been advanced for the maintenance of this exceptional level of genetic variation, one of which suggests that it is necessary for successful eutherian reproduction. Marsupials (metatherians) and eutherians are the only two groups of viviparous mammals, but their modes of reproduction are quite distinct. Although marsupials have placentae, they are generally shorter lived and less invasive than in eutherians. Other investigations have shown that genetic variation at marsupial MHC class I loci is probably high. Weak or non-existent mixed lymphocyte culture responses previously reported in several marsupial species have suggested a lack of class II variation. Data have therefore been collected on the level of restriction fragment length polymorphism at MHC class II beta-chain encoding loci of a marsupial, Macropus eugenii (the tammar wallaby). This level is shown to be low, between the level of MHC variation found in cheetahs and a population of lions with a restricted genetic base. Attention is drawn to the need to collect more data on the level of class II variability in both eutherians and marsupials, and to the potential of marsupials for understanding the relation, if any, between mode of reproduction and MHC variability.
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Renfree, MB. "Monotreme and marsupial reproduction." Reproduction, Fertility and Development 7, no. 5 (1995): 1003. http://dx.doi.org/10.1071/rd9951003.
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Marsupials were regarded as curiosities by their early European discoverers, animals to be wondered at. Monotremes were even more surprising; the platypus was such an amalgam of characters that it was thought to be a hoax. They were recognized very early as mammals that could make a major contribution to our understanding of reproductive processes, and work on marsupials at the turn of the century was much in evidence. It is, however, only in the past two decades, and especially in the past few years that marsupial research has regained this position. There is no doubt that future research will strengthen this contribution, but we are faced with serious conservation questions that must be solved if we are to maintain these wonderful animals as a resource for future generations.
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Rodger, JC. "Prospects for the Artificial Manipulation of Marsupial Reproduction and Its Application in Research and Conservation." Australian Journal of Zoology 37, no. 3 (1989): 249. http://dx.doi.org/10.1071/zo9890249.
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Techniques to manipulate reproduction and productivity are well established features of the husbandry of domestic animals and the treatment of human infertility. Similar approaches are feasible in marsupials, but little work has been done to apply our considerable basic knowledge of marsupial reproduction to produce practical artificial breeding. If the reproduction and productivity of marsupials could be more effectively controlled it would greatly aid research and profoundly change both current practice in the management of zoo animals, and the strategies employed for the breeding and conservation of rare or endangered species. The present paper sets out the likely agenda, reports progress to date and discusses short and long-term prospects for the artificial breeding of marsupials. Topics discussed include: induced ovulation and superovulation, oocyte and embryo collection, semen collection and the frozen storage of sperm, artificial insemination, in vitro fertilization and embryo transfer, frozen storage of embryos, and the use of surrogate mothers in supporting both pregnancy to term, and the development of young in the pouch.
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Behringer, Richard R., Guy S. Eakin, and Marilyn B. Renfree. "Mammalian diversity: gametes, embryos and reproduction." Reproduction, Fertility and Development 18, no. 2 (2006): 99. http://dx.doi.org/10.1071/rd05137.
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The class Mammalia is composed of approximately 4800 extant species. These mammalian species are divided into three subclasses that include the monotremes, marsupials and eutherians. Monotremes are remarkable because these mammals are born from eggs laid outside of the mother’s body. Marsupial mammals have relatively short gestation periods and give birth to highly altricial young that continue a significant amount of ‘fetal’ development after birth, supported by a highly sophisticated lactation. Less than 10% of mammalian species are monotremes or marsupials, so the great majority of mammals are grouped into the subclass Eutheria, including mouse and human. Mammals exhibit great variety in morphology, physiology and reproduction. In the present article, we highlight some of this remarkable diversity relative to the mouse, one of the most widely used mammalian model organisms, and human. This diversity creates challenges and opportunities for gamete and embryo collection, culture and transfer technologies.
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Tyndale-Biscoe, C. H. "Australasian marsupials - to cherish and to hold." Reproduction, Fertility and Development 13, no. 8 (2001): 477. http://dx.doi.org/10.1071/rd01079.
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Considerable interchange of mammals between South America and Australasia occurred during the first half of the Tertiary, including the presence of placental mammals in Australia. This challenges the old assumption that the marsupial radiation in Australia was made possible by the absence of placental competition, and suggests that two properties of marsupial organization may have favoured their survival in the increasingly arid climates that developed after the separation of Australasia from Antarctica. The basal metabolic rates of marsupials are about 70% of equivalent placentals, so their maintenance requirements for energy, nitrogen and water are lower, whereas their field metabolic rates are about the same, which means that they have a greater metabolic scope to call on when active. This may have given marsupials an advantage in semi-arid environments. The lengthy and complex lactation of marsupials enables the female to exploit limited resources over an extended period without compromising the survival of the young. Both these properties of marsupials enabled them to survive the double constraints of low fertility soils and the uncertain climate of Australia throughout the Tertiary. The arrival of people was followed first by the extinction of the large marsupials and, much later, by the wholesale decline or extinction of the small-to-medium sized species. The common factor in both extinctions may have been the constraints of marsupial reproduction.
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Edwards, Melanie J., and Janine E. Deakin. "The marsupial pouch: implications for reproductive success and mammalian evolution." Australian Journal of Zoology 61, no. 1 (2013): 41. http://dx.doi.org/10.1071/zo12088.
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Extant mammals are divided into sub- and infraclasses that are distinguished by their mode of reproduction. The monotremes lay eggs, the marsupials give birth to altricial young that typically develop in a pouch, and the eutherians have prolonged in utero development, resulting in well developed young at birth. The three groups exhibit what appears to be a nice progression of evolution towards the well developed newborn young of eutherian mammals. However, marsupials do not represent a step in the progression of producing well developed young, but maintain a reproductive strategy that has evolved to prosper in their specific niche. The production of undeveloped young with increased development in the pouch (or counterpart) provides specific advantages to those species living in diverse environments. The evolution of this reproductive strategy provides a clever solution to the uncertain and often adverse conditions encountered by many species, and the survival of the developing young in a pouch containing potentially harmful microorganisms is truly remarkable. In this review, we explore the unique features of the pouch, highlight the research questions that remain unanswered regarding this unique marsupial attribute and discuss the advantages of the marsupial reproductive strategy and the potential role of the pouch in mammalian diversification.
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Renfree, Marilyn B. "WOMEN IN REPRODUCTIVE SCIENCE: Reproduction down under." Reproduction 158, no. 6 (December 2019): F127—F137. http://dx.doi.org/10.1530/rep-19-0230.
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Australia is home to a unique assembly of mammals – the marsupials and monotremes. Despite this uniqueness, they have been largely ignored by the biomedical scientific community, and yet study of marsupials has contributed to modern research on reproduction, development, evolution, conservation, molecular and comparative genomics. My lifetime passion for these long-neglected Australian fauna has led to unexpected discoveries and insights that challenged assumptions and opened up new areas of international research. I used a range of disciplinary expertise to pursue the study of these unique mammals. My main experimental species has been the tammar wallaby that I have used as a model species to investigate and understand not only biomedical problems but also to provide knowledge that is critical for the continued conservation and management of Australia’s dwindling native mammals. This model provided more than a few surprises for me and my wonderful team of students, post-docs and collaborators about how hormones, genes and signalling molecules control reproductive biology and development in a wider context as well as how the interactions of the environment with mother and conceptus, with mother and fetus and mother and young ultimately control most aspects of successful reproduction in mammals.
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Rodger, John C. "Likely targets for immunocontraception in marsupials." Reproduction, Fertility and Development 9, no. 1 (1997): 131. http://dx.doi.org/10.1071/r96073.
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There is a growing need to manage marsupial populations as a means to mitigate economic and environmental damage and resolve animal welfare problems. In Australia, the problems of population management are highly specific and localized. In contrast, in New Zealand the problem is the control of the many millions of widely-distributed brushtail possums which are the country’s major vertebrate pest. The needs of the two countries are thus very different but immunocontraception may provide an effective and humane alternative to current lethal control strategies. This paper discusses the features of marsupial reproduction and development that offer potential as targets for immunocontraceptive interference, including: (1) sperm production and maturation in the male; (2) sperm transport and maturation in the female; and (3) sperm and egg antigens and the early embryo. Some of these antigen targets are shared with eutherian mammals but others are likely to be unique to marsupials.
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Shaw, Geoff, and Marilyn B. Renfree. "Parturition and perfect prematurity: birth in marsupials." Australian Journal of Zoology 54, no. 3 (2006): 139. http://dx.doi.org/10.1071/zo05070.
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Marsupials are distinguished from eutherian mammals in their mode of reproduction. They give birth to a highly altricial young, which completes its development whilst attached to a teat, usually within a pouch. The marsupial neonate has relatively well-developed digestive, respiratory and circulatory systems but retains its fetal excretory system with a fully functional mesonephric kidney and undifferentiated gonads and genitalia. We have investigated birth in the tammar wallaby (Macropus eugenii) and shown that the tiny (400 mg) fetus determines the time of its own delivery. Although plasma progesterone falls, and oestradiol associated with the postpartum oestrus typically rises, around the time of parturition, neither hormone is essential for the timing of birth. However relaxin may loosen the connective tissue of the cervix and vaginae for birth. Labour starts suddenly and is completed within minutes. Both prostaglandins and mesotocin are essential for the contractions that deliver the young. Prostaglandins from the reproductive tract act via the brain to control parturient behaviour. In the last 2 days of gestation fetal adrenal glucocorticoid production increases, promoting lung maturation and surfactant production and ultimately triggering labour. The accessibility of the altricial neonatal marsupial provides a unique opportunity for experimental manipulation of organ development and maturation.
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Bradshaw, Felicity J., and Don Bradshaw. "Progesterone and reproduction in marsupials: A review." General and Comparative Endocrinology 170, no. 1 (January 2011): 18–40. http://dx.doi.org/10.1016/j.ygcen.2010.07.015.
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Ferreira, Mariana Silva, Rui Cerqueira, and Marcus Vinícius Vieira. "What are the main drivers of survival and recruitment in tropical forest marsupials? A 16-year study." Journal of Mammalogy 101, no. 2 (February 22, 2020): 515–25. http://dx.doi.org/10.1093/jmammal/gyaa013.
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Abstract Tropical forest marsupials exhibit large interannual variation in population sizes, with direct negative density dependence capturing the essential features of their dynamics. However, the demographic mechanisms underlying population growth rate and driving both survival and reproduction are still unclear. We used a 16-year capture-mark-recapture data set for five tropical forest marsupials to test for seasonal and interannual density dependence in survival and recruitment. Hypotheses regarding the effects of exogenous (rainfall and minimum temperature) factors on survival, recruitment, and reproductive parameters (fecundity, litter size, and proportion of reproductive females) were also tested. Population size negatively affected survival in three of five species. High population sizes in a given year reduced survival rates in the following year, with strong detrimental effects on males. Recruitment and proportion of reproductive females were highly dependent on weather variables, and were not affected by previous population sizes (except for Metachirus nudicaudatus). Fecundity (number of female offspring/female) was related negatively to population size only in the black-eared opossum (Didelphis aurita), while litter size was a relatively conservative parameter, largely independent of external conditions. Our analyses indicate that density-dependent survival is the mechanism that regulates population size of tropical forest marsupials, either through a reduction in survival or an increase in emigration rates. This general regulatory mechanism may be common to other marsupials in the Atlantic Forest and other tropical forests. Marsupiais de florestas tropicais exibem grande variação interanual nos tamanhos populacionais, com dependência negativa e direta da densidade capturando a essência de sua dinâmica populacional. No entanto, os mecanismos demográficos subjacentes à taxa de crescimento populacional e determinantes da sobrevivência e reprodução ainda são incertos. Nós usamos 16 anos de dados de captura-marcação-recaptura de cinco espécies de marsupiais de florestas tropicais para avaliar a dependência de densidade sazonal e interanual na sobrevivência e recrutamento. Hipóteses sobre efeitos de fatores exógenos (pluviosidade e temperatura mínima) na sobrevivência, recrutamento e parâmetros reprodutivos (fecundidade, tamanho da ninhada e proporção de fêmeas reprodutivas) também foram testadas. O tamanho da população afetou negativamente a sobrevivência em três das cinco espécies. O tamanho populacional elevado em um ano reduziu as taxas de sobrevivência no ano seguinte, com efeitos mais negativos nos machos. Recrutamento e proporção de fêmeas reprodutivas foram dependentes das variáveis climáticas e não foram afetados pelos tamanhos populacionais anteriores (com exceção de Metachirus nudicaudatus). A fecundidade (número de filhotes fêmea/fêmea) foi relacionada negativamente ao tamanho da população do gambá-de-orelha-preta (Didelphis aurita), enquanto o tamanho da ninhada foi um parâmetro relativamente conservador e independente das condições externas. Nossas análises indicam que a sobrevivência dependente da densidade regula as populações de marsupiais em florestas tropicais, seja através da redução na sobrevivência ou no aumento da emigração. Esse mecanismo regulatório pode ser comum a outros marsupiais na Mata Atlântica e outras florestas tropicais.
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D’Andrea, PS, R. Gentile, LS Maroja, FA Fernandes, R. Coura, and R. Cerqueira. "Small mammal populations of an agroecosystem in the Atlantic Forest domain, southeastern Brazil." Brazilian Journal of Biology 67, no. 1 (February 2007): 179–86. http://dx.doi.org/10.1590/s1519-69842007000100025.
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This study reports 2 years of the population dynamics and reproduction of a small mammal community using the removal method. The study was conducted in a rural area of the Atlantic Forest, in Sumidouro, Rio de Janeiro State, Brazil. The population sizes, age structure and reproduction were studied for the four most common species in the study area. The overall diversity was 1.67 and ranged between 0.8 to 1.67. The species richness was 13 considering the whole study. The most abundant species were the rodents Nectomys squamipes (n = 133), Akodon cursor (n = 74), Oligoryzomys nigripes (n = 25) and the marsupials Didelphis aurita (n = 58) and Philander frenatus (n = 50). Seven other rodents were captured once: Necromys lasiurus, Akodon montensis, Sooretamys angouya, Oecomys catherine, Oxymycterus judex, Euryzygomatomys spinosus and Trinomys iheringi. There were higher peaks for diversity and species richness during the winter (dry) months, probably due to higher food availability. The marsupials had a seasonal reproduction with highest population sizes at the end of the rainy seasons. Nectomys squamipes reproduced mostly during rainy periods. Akodon cursor reproduced predominantly in the winter with the highest population peaks occurring during this season. The analysis of the population dynamics of the rodent species indicated that no species behaved as an agricultural pest, probably due to the heterogeneous landscape of high rotativity of vegetable cultivation. Rodent populations were more susceptible to the removal procedure than marsupial ones.
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Belov, Katherine, Gavan A. Harrison, and Desmond W. Cooper. "Short Communication: Cloning of the red kangaroo (Macropus rufus) follicle stimulating hormone beta subunit." Reproduction, Fertility and Development 10, no. 3 (1998): 289. http://dx.doi.org/10.1071/r98067.
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The cDNA encoding the follicle stimulating hormone beta subunit (FSH-β) was isolated from a red kangaroo pituitary cDNA library by using a porcine probe and the nucleotide sequence for the coding region was determined. The highest degree of deduced amino acid sequence identity (91%) was observed between the red kangaroo and another marsupial, the brushtail possum (Trichosurus vulpecula), followed by eutherian species (76%, 75% and 74%, respectively, for pig, mouse and sheep). Based on the deduced red kangaroo FSH-β amino acid sequence, putative antigenic sites have been identified that may prove useful for studying the hormonal control of reproduction in marsupials.
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Renfree, Marilyn B., Andrew J. Pask, and Geoffrey Shaw. "Sex down under: the differentiation of sexual dimorphisms during marsupial development." Reproduction, Fertility and Development 13, no. 8 (2001): 679. http://dx.doi.org/10.1071/rd01096.
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Marsupials have many characteristic features that make them ideal models to study the control of sexual differentiation and development. They are distinguished from eutherian mammals in their mode of reproduction and their greater dependence on the teat and mammary gland than on the placenta for development. They give birth to a highly altricial young which completes its development while firmly attached to a teat, usually within the confines of a pouch. At birth, the marsupial neonate has a well-developed digestive, respiratory and circulatory system, but retains its fetal excretory system with a fully functional mesonephric kidney and undifferentiated gonads and genitalia.
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McNab, Brian K. "Food habits, energetics, and the reproduction of marsupials." Journal of Zoology 208, no. 4 (August 20, 2009): 595–614. http://dx.doi.org/10.1111/j.1469-7998.1986.tb01526.x.
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Gemmell, RT. "A comparative study of the corpus luteum." Reproduction, Fertility and Development 7, no. 3 (1995): 303. http://dx.doi.org/10.1071/rd9950303.
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The corpus luteum (CL) is a transitory organ which has a regulatory role in reproduction. Sharks, amphibians and reptiles have corpora lutea that produce progesterone which influences the rate of embryonic development. The egg-laying monotremes and the two major mammalian groups, eutherian and marsupial, have a CL that secretes progesterone. Most eutherians have allowed for the uterine development of their young by extending the length of the oestrous cycle and the CL or placenta actively secretes progesterone until birth. Gestation in the marsupial does not extend beyond the length of an oestrous cycle and the major part of fetal development takes place in the pouch. Where the extension of the post-luteal phase in the eutherian has allowed for the uterine development of young, the marsupial has extended the pre-luteal phase of the oestrous cycle and has evolved an alternative reproductive strategy, embryonic diapause. The mechanism for the secretion of hormones from the CL has been controversial for many years. Densely-staining secretory granules have been observed in the CL of sharks, marsupials and eutherians. These granules have been reported to contain relaxin, oxytocin or mesotocin, and progesterone. A hypothesis to suit all available data is that all hormones secreted by the CL are transported within such granules. In conclusion, although there are obvious differences in the mode of reproduction in the two main mammalian groups, it is apparent that there is a great deal of similarity in the hormonal control of regression of the CL and parturition.
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Witt, R. R., L. A. Hinds, and J. C. Rodger. "93 Oestrous Synchronisation Studies in a Marsupial." Reproduction, Fertility and Development 30, no. 1 (2018): 186. http://dx.doi.org/10.1071/rdv30n1ab93.
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There is no strategy to precisely synchronise and predict oestrus and ovulation in marsupials. This is the major limitation in applying assisted reproduction to marsupial conservation. Routine methods of female synchronization that target the ovary (effective in eutherians) are ineffective in marsupials because they do not disrupt the corpus luteum. Gondaotropin-releasing hormone (GnRH) agonists have been used to suppress female cycling in several marsupials and work by targeting GnRH action in the pituitary. After the GnRH agonist reaches its active endpoint, female cycling returns. This study investigated whether Lucrin Depot (Abbott Laboratories, Lake Bluff, IL, USA), a tailored 1-month microsphere GnRH agonist preparation, has the potential to first suppress female cycling, and then facilitate a synchronous return to female cycling in a model marsupial, the tammar wallaby (Macropus eugenii). Preliminary studies indicated that Lucrin could be used to regulate ovarian activity, but a dose >0.20 mg kg−1 was required. In this study, nonpregnant tammars (n = 18, 6 per group) had their pouch young removed (RPY) on Day 0; RPY suspends lactation and reactivates cycling, allowing for controlled assessment of oestrus and mating in treated and untreated females. On Day 0, an intramuscular (IM) injection of water (Control) or 1 mg kg−1 of Lucrin Depot (group A) was given after RPY. Group B also received 1 mg kg−1 of Lucrin Depot but this was not injected until Day 10 after RPY (a strategy to assess whether timing of Lucrin yields different results). Females were placed in breeding pens of 1 male to 3 females. Reproductive suppression and synchrony of return to female cycling was assessed by pouch and urogenital opening checks to detect newborn young and copulatory plugs. All data (time of mating/conception) were analysed using ANOVA (significance, P < 0.05). There was a significant difference between the first mating response in the Control compared with Groups A and B (P = 0.0003), but the time from Lucrin injection to mating, Day 0 or Day 10, was not significant (P = 0.1431). All control females mated before Day 32 RPY, whereas all Lucrin-treated females mated from Day 33 to 66. All Lucrin-treated females conceived as evidenced by pouch young. Further analysis revealed 2 Lucrin-injection to mating response intervals, those females delayed by ~10 days that conceived between 33 and 50 days (n = 7: 41 ± 2.1 days; mean ± SEM), and those females delayed by ~30 days that conceived between 61 and 66 days (n = 5: 62 ± 1.0 days; mean ± SEM) following injection. Thus, an IM injection of 1 mg kg−1 of Lucrin Depot is sufficient to delay oestrus in breeding tammar wallabies whether given at the time of RPY or 10 days later. This study confirmed that Lucrin Depot can be used to regulate ovarian activity in macropod marsupials, and has potential to form the basis of a GnRH agonist-based synchronisation strategy for use in assisted breeding for marsupial conservation. This research was supported by Holsworth Wildlife Research Endowment.
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Menzies, Brandon R., Thomas B. Hildebrandt, and Marilyn B. Renfree. "Unique reproductive strategy in the swamp wallaby." Proceedings of the National Academy of Sciences 117, no. 11 (March 2, 2020): 5938–42. http://dx.doi.org/10.1073/pnas.1922678117.
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Reproduction in mammals requires distinct cycles of ovulation, fertilization, pregnancy, and lactation often interspersed with periods of anoestrus when breeding does not occur. Macropodids, the largest extant species of marsupials, the kangaroos and wallabies, have a very different reproductive strategy to most eutherian mammals whereby young are born at a highly altricial stage of development with the majority of development occurring over a lengthy lactation period. Furthermore, the timings of ovulation and birth in some species occurs within a very short interval of each other (sometimes hours). Female swamp wallabies have an oestrous cycle shorter than their pregnancy length and were, therefore, speculated to mate and form a new embryo before birth thereby supporting two conceptuses at different stages of pregnancy. To confirm this, we used high-resolution ultrasound to monitor reproduction in swamp wallabies during pregnancy. Here, we show that females ovulate, mate, and form a new embryo prepartum while still carrying a full-term fetus in the contralateral uterus. This embryo enters embryonic diapause until the newborn leaves the pouch 9 mo later. Thus, combined with embryonic diapause, females are continuously pregnant and lactating at the same time throughout their reproductive life, a unique reproductive strategy that completely blurs the normal staged system of reproduction in mammals.
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Hearn, C. M., G. Shaw, R. V. Short, and M. B. Renfree. "Effects of cabergoline on reproduction in three families of Australian marsupials." Reproduction 113, no. 1 (May 1, 1998): 151–57. http://dx.doi.org/10.1530/jrf.0.1130151.
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Menkhorst, E., N. Ezard, and L. Selwood. "Induction of ovulation and natural oestrous cycling in the Stripe-faced Dunnart, Sminthopsis macroura." Reproduction 133, no. 2 (February 2007): 495–502. http://dx.doi.org/10.1530/rep-06-0254.
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Induced ovulation allows reproduction by otherwise infertile females, and is ideal for the captive breeding of endangered species where the population is aged or breeding is unsuccessful. A predictable time of ovulation after induction has not yet been achieved in polyovular marsupials. Ovulation was induced in Sminthopsis macroura using an initial injection of 20 IU equine serum gonadotrophin (eSG; Day 0), followed on Day 4 by either 20 IU eSG (n = 25) or 0.5 mg porcine luteinizing hormone (n = 26). I.p. hormone injection was given in the morning or early evening, and reproductive status was established prior to induction. Five non-cyclic animals began to cycle naturally following induction and one gave birth to a litter. The time of ovulation after the 1st injection (7.8 ± 0.9 days) was significantly shorter (P = 0.000) and less variable than the previous study, mimicked the timing of natural cycling, and both natural and induced animals ovulated in the early morning. In vitro oocyte movement through the oviduct, observed for the first time in a marsupial, occurred in pulses. We estimated one group of oocytes could travel the length of the oviduct in 40 min, but it was probably around 4 h. The entire ovulation time (including multiple ovulations) was estimated at 7.5 h. This study has achieved a predictable timing of ovulation after stimulation, and induced noncyclic animals to cycle naturally and give birth, providing a modified methodology for use in captive breeding programs of endangered dasyurid marsupial species with low fecundity.
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McAllan, B. M. "Dasyurid marsupials as models for the physiology of ageing in humans." Australian Journal of Zoology 54, no. 3 (2006): 159. http://dx.doi.org/10.1071/zo05073.
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Marsupials of the order Dasyuromorphia have features that make them useful as models for ageing processes in humans. First, they are long-lived for their size, with most small species living for at least 1 year, often several years, contrasting with the mouse, a conventional model for ageing studies, where most populations turn over within 4–6 months. Longevity in some dasyurids allows biological comparisons with other long-lived mammals. Second, the predictable reproduction and life histories of the genera Antechinus and Sminthopsis allow analysis of the role of sex hormones in physiological changes as ageing progresses. For Antechinus, this includes the interaction between testosterone and cortisol in initiating pathologies in males but not females. Many ageing processes are expressed differently between male and female humans, and have a stress component. The neuropathological changes that occur in Antechinus can be used as a model for the dementias of ageing, including Alzheimer’s disease. The age-related neuropathologies in Antechinus indicate that hormonal influences may be important. Finally, in Sminthopsis, the interaction between sex hormones, reproduction and the fattening season offer insights into the interaction between longevity and reduced energy intake, including obesity. Thus these mammals offer useful models for many of the possible influences for healthy ageing in humans.
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Griffith, Oliver W., Arun R. Chavan, Mihaela Pavlicev, Stella Protopapas, Ryan Callahan, Jamie Maziarz, and Günter P. Wagner. "Endometrial recognition of pregnancy occurs in the grey short-tailed opossum ( Monodelphis domestica )." Proceedings of the Royal Society B: Biological Sciences 286, no. 1905 (June 19, 2019): 20190691. http://dx.doi.org/10.1098/rspb.2019.0691.
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In human pregnancy, recognition of an embryo within the uterus is essential to support the fetus through gestation. In most marsupials, such as the opossums, pregnancy is shorter than the oestrous cycle and the steroid hormone profile during pregnancy and oestrous cycle are indistinguishable. For these reasons, it was assumed that recognition of pregnancy, as a trait, evolved in the eutherian (placental) stem lineage and independently in wallabies and kangaroos. To investigate whether uterine recognition of pregnancy occurs in species with pregnancy shorter than the oestrous cycle, we examined reproduction in the short-tailed opossum ( Monodelphis domestica ), a marsupial with a plesiomorphic mode of pregnancy. We examined the morphological and gene expression changes in the uterus of females in the non-pregnant oestrous cycle and compared these to pregnancy. We found that the presence of an embryo did not alter some aspects of uterine development but increased glandular activity. Transcriptionally, we saw big differences between the uterus of pregnant and cycling animals. These differences included an upregulation of genes involved in transport, inflammation and metabolic-activity in response to the presence of a fetus. Furthermore, transcriptional differences reflected protein level differences in transporter abundance. Our results suggest that while the uterus exhibits programmed changes after ovulation, its transcriptional landscape during pregnancy responds to the presence of a fetus and upregulates genes that may be essential for fetal support. These results are consistent with endometrial recognition of pregnancy occurring in the opossum. While the effects on maternal physiology appear to differ, recognition of pregnancy has now been observed in eutherian mammals, as well as, Australian and American marsupials.
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Julien-Laferriere, Didier, and Martine Atramentowicz. "Feeding and Reproduction of Three Didelphid Marsupials in Two Neotropical Forests (French Guiana)." Biotropica 22, no. 4 (December 1990): 404. http://dx.doi.org/10.2307/2388558.
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Woolley, PA. "Reproduction in Dasykaluta-Rosamondae (Marsupialia, Dasyuridae) - Field and Laboratory Observations." Australian Journal of Zoology 39, no. 5 (1991): 549. http://dx.doi.org/10.1071/zo9910549.
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Observations on reproduction in both wild-caught and laboratory-maintained Dasykaluta rosamondae have led to the conclusion that this species is one of 10 dasyurid marsupials in which males die soon after their first mating period. D. rosamondae have a short annual breeding season. The females are monoestrous, mating in September and bearing the young in November. Laboratory-reared young are weaned at an age of about 3 1/2-4 months, in February and March, and juveniles appear in the field population at this time. Both mates and females reach sexual maturity at an age of about 10 months. In the laboratory, males breed in only one season, after which those that survive become reproductively senile. Mature males disappear from the field population about the time the young are born; those collected shortly before this show signs of reproductive senescence. Males collected in the months after the young are weaned represent a single age-class; their reproductive development parallels that of maturing known-age males. Females are capable of breeding in at least two seasons and litters of up to eight are reared. Development of the pouch young is described. Unusual interstitial tissue masses develop in the ovaries of D. rosamondae; the granulosa cells of some follicles undergo transformation to interstitial cells, and the oocytes in these follicles degenerate, shortly before the females enter oestrus.
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Woolley, PA. "Observations On The Reproductive Biology Of Myoictis Albopunctatus And Dasyurus Spartacus, Dasyurid Wallacei, Neophascogale Lorentzi, Dasyurus Marsupials Endemic To New Guinea." Australian Mammalogy 23, no. 1 (2001): 63. http://dx.doi.org/10.1071/am01063.
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FIELD and laboratory observations on the reproductive biology of seven species of dasyurid marsupials endemic to New Guinea (viz. ?Antechinus? habbema, ?Antechinus? melanurus, ?Antechinus? naso, Murexia longicaudata, Murexia rothschildi, Myoictis melas and Phascolosorex dorsalis) have been recorded by Woolley (in press). Here, less detailed observations on another four, previously unstudied, species (Myoictis wallacei, Neophascogale lorentzi, Dasyurus albopunctatus and Dasyurus spartacus) are presented to provide information on some aspects of reproduction in each species. Only a small number of individuals of each species were trapped, or collected by other means, and maintained in captivity (Table 1). The methods used for trapping and maintenance can be found in Woolley (1993), and for the observations made on the animals, Woolley (in press). Captive breeding could not be attempted because only one sex of each species was maintained. The limited reproductive data obtained from individuals at the time of capture, and from captive animals, is summarised for males in Table 2 and Fig. 1, and for females in Table 3.
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Oliveira, Francisco F. R., Rafael Nessim, Leonora P. Costa, and Yuri Luiz R. Leite. "Small mammal ecology in an urban Atlantic forest fragment in southeastern Brazil." Lundiana: International Journal of Biodiversity 8, no. 1 (October 28, 2007): 27–34. http://dx.doi.org/10.35699/2675-5327.2007.23171.
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We conducted a capture-mark-release study of small mammals in an urban forest fragment at the Parque das Mangabeiras, in the city of Belo Horizonte, southeastern Brazil. Four marsupials — Didelphis albiventris Lund, Gracilinanus agilis (Burmeister), Marmosops incanus (Lund), Philander frenatus (Olfers) — and four rodents — Sciurus aestuans Linnaeus, Akodon montensis Thomas, Rhipidomys mastacalis (Lund) and Mus musculus Linnaeus — were found between March 2003 and February 2004. The most abundant species were M. incanus and S. aestuans, representing respectively 50% and 20% of the individuals recorded. Terrestrial habits were detected for A. montensis and D. albiventris, scansorial habits for G. agilis, M. incanus, P. frenatus, and S. aestuans, while R. mastacalis was exclusively arboreal. There was positive correlation between rainfall and population abundance for D. albiventris, and positive correlation between recruitment rates and rainfall for M. incanus. Rapid turnover rates suggested short residence time for most species. Three reproductive patterns were identified: prolonged reproduction during both seasons in R. mastacalis, reproduction during the dry season in G. agilis, and reproduction during the wet season in the remaining species. Only individuals of D. albiventris, M. incanus, R. mastacalis, and S. aestuans were detected across the paved road that runs through the fragment, suggesting that the road may be a barrier to the other species.
Keywords: small mammals, secondary forest, community ecology, population dynamics, seasonality.
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Herbert, C. A., T. E. Trigg, M. B. Renfree, G. Shaw, D. C. Eckery, and D. W. Cooper. "Long-term effects of deslorelin implants on reproduction in the female tammar wallaby (Macropus eugenii)." Reproduction 129, no. 3 (March 2005): 361–69. http://dx.doi.org/10.1530/rep.1.00432.
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The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 ± 87 days after treatment with a 5 mg deslorelin implant (n= 7), while control animals gave birth to their first young 159 ± 47 days after placebo implant administration (n= 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release deslorelin implants. The effects of deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.
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Cheung, Timothy C., and John P. Hearn. "Molecular cloning and tissue expression of the gonadotrophin-releasing hormone receptor in the tammar wallaby (Macropus eugenii)." Reproduction, Fertility and Development 14, no. 3 (2002): 157. http://dx.doi.org/10.1071/rd01124.
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Gonadotrophin-releasing hormone (GnRH) plays a pivotal role in the endocrine control of both reproduction and embryonic development. This first study of the marsupial GnRH receptor (GnRH-R) gene in the tammar wallaby provides information on the complex molecular events that regulate hypothalamic-pituitary- gonadal function in marsupials, and allows a comparison with eutherian mammals. Two identical wallaby GnRH-R cDNA clones were obtained, one isolated from cDNA generated from the testis of a 79-day-old pouch young and the other from the pituitary of an adult. Wallaby GnRH-R is composed of 328 amino acid residues. Sequence analysis showed that wallaby GnRH-R contains 7 transmembrane domains and is a member of the G protein- coupled receptor family. A putative protein kinase A phosphorylation site and a putative protein kinase C (PKC) phosphorylation site were found in the first intracellular loop, and an additional PKC phosphorylation site was located in the third intracellular loop. Comparisons with the eutherian GnRH-Rs show a greater diversity in the N-terminal extracellular domain. Wallaby GnRH-R has approximately 80% amino acid sequence homology with eutherian GnRH-Rs and 93% homology with the brush-tail possum, another member of the Diprotodontia semiorder.
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Pickett, Karolyne N., David S. Hik, Alan E. Newsome, and Roger P. Pech. "The influence of predation risk on foraging behaviour of brushtail possums in Australian woodlands." Wildlife Research 32, no. 2 (2005): 121. http://dx.doi.org/10.1071/wr03098.
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The potential effects of predation risk on common brushtail possums were investigated in south-eastern Australian woodlands. Patterns of habitat use, foraging costs using giving-up density (GUD) experiments, and indices of body condition and reproductive success were examined at eight sites in two habitat types (eucalypt- or cypress-pine–dominated stands), within three areas of different red fox abundance (high, moderate and low fox density). In cypress-pine–dominated stands, possums travelled further on the ground, visited more feeding stations and had lower GUDs at feeders where foxes were removed than did possums in high-fox-density sites. In contrast, there was no effect of fox removal on the behaviour of possums in eucalypt-dominated stands. Fox removal also had no effect on indices of body condition and reproduction. Minor effects of microhabitat were detected with trackplot and GUD experiments, but, overall, the results suggest that habitat at the stand-level was more important. The non-lethal effects of foxes in different habitats may need to be taken into account when developing conservation strategies for native marsupials.
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Rafli, Fahry, Angel Novita Tethool, and Freddy Pattiselanno. "Morphometry of The Reproductive Organs of Female Bandicoots (Echymipera kalubu)." Jurnal Veteriner 22, no. 4 (December 30, 2021): 562–67. http://dx.doi.org/10.19087/jveteriner.2021.22.4.562.
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Information about bandicoots in Papua is very limited, because most of the studies conducted are focusing on ecology with study areas in other parts of Indonesia New Guinea. Our knowledge about the reproductive organs of bandicoots, especially females as a local genetic source, is almost completely non-existent. Meanwhile, on the other hand, the development of captive breeding efforts for endemic Papuan animals including bandicoots is currently a concern. Therefore, research on the reproductive organs of female bandicoots is very urgent to get an idea of the reproductive organs that play an important role in the development of captive breeding program. This research was conducted at the Laboratory of Physiology and Animal Reproduction, Faculty of Animal Husbandry, University of Papua from 15 June to 15 September 2017. The reproductive organs of female bandicoots were obtained from female bandicoots hunted around Manokwari. Three female reproductive organs of the bandicoot (Echymipera kalubu) were used in this study, and the morphology of their reproductive organs was observed according to the purpose of the study. As a comparison the reproductive organs of D. minustus were used in this study. The results showed that the female reproductive organs of E. kalubu had an “advanced duplex” type with a pair of ovaries, fallopian tubes, uterus, vaginal cul de sac, cervix and lateral vagina. Morphologically, the reproductive organs of E. kalubu have a certain uniqueness, different from the reproductive organs of other female marsupials, so they need serious attention in developing captive breeding program in the near future.
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Gentile, Rosana, Paulo Sergio D'Andrea, Rui Cerqueira, and Luana Santoro Maroja. "Population dynamics and reproduction of marsupials and rodents in a Brazilian rural area: a five-year study." Studies on Neotropical Fauna and Environment 35, no. 1 (April 1, 2000): 1–9. http://dx.doi.org/10.1076/0165-0521(200004)35:1;1-m;ft001.
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Nave, C. D., G. Shaw, R. V. Short, and M. B. Renfree. "Contraceptive effects of levonorgestrel implants in a marsupial." Reproduction, Fertility and Development 12, no. 2 (2000): 81. http://dx.doi.org/10.1071/rd00045.
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The effect of subcutaneous levonorgestrel implants on reproduction in female tammar wallabies was investigated during the breeding and non-breeding season. Female tammars were given either a control or a levonorgestrel implant and their pouch young were removed to terminate embryonic diapause. Both the control and the levonorgestrel-implant animals treated during the months of May and June gave birth, demonstrating that levonorgestrel does not prevent the reactivation of the diapausing blastocyst or its subsequent development when given at these times. However, none of the levonorgestrel-treated animals mated post partum, whereas all of the control females that gave birth had a post partum oestrus and mated. Control animals gave birth again when the neonate was removed, and continued to breed normally during the following 36 months of the investigation. None of the levonorgestrel-treated animals gave birth again or mated during the next 36 months. Animals given control implants during December did not reactivate or give birth until the normal start of the breeding season in late January. Animals treated with levonorgestrel implants during December did not reactivate with the control animals at the beginning of the breeding season and did not give birth during the next 36 months. There were no effects of lev-onorgestrel treatment on early lactation. Levonorgestrel implants were removed from six females and four of these animals resumed reproductive activity, confirming that the contraceptive effect of the implants is reversible. Levonorgestrel implants therefore provide a highly effective, reversible and long-term method of contraception for tammar wallabies. This contraceptive system appears to offer a method of population control for the management of overabundant captive and selected wild populations of macropodid marsupials.
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Barros, Camila S., Renato Crouzeilles, and Fernando A. S. Fernandez. "Reproduction of the opossums Micoureus paraguayanus and Philander frenata in a fragmented Atlantic Forest landscape in Brazil: Is seasonal reproduction a general rule for Neotropical marsupials?" Mammalian Biology 73, no. 6 (November 2008): 463–67. http://dx.doi.org/10.1016/j.mambio.2007.08.002.
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Cowan, PE. "Changes in milk composition during lactation in the common brushtail possum, Trichosurus vulpecula (Marsupialia: Phalangeridae)." Reproduction, Fertility and Development 1, no. 4 (1989): 325. http://dx.doi.org/10.1071/rd9890325.
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The milk constituents of Trichosurus vulpecula, a folivorous marsupial, showed marked quantitative and qualitative changes during the course of lactation. The milk produced in the early stages of lactation was dilute, with about 9-13% (w/w) solids during the first 3 weeks, comprising mostly carbohydrate and protein (35-40%). At 20 weeks, about three-quarters of the way through lactation, the milk was much more concentrated, about 28% solids, with lipid the predominant fraction (30-35%), after a marked decline in carbohydrate content (20-25%). Concentrations of the electrolytes sodium and potassium also underwent marked changes. The changes in milk composition of T. vulpecula during the first three-quarters of lactation were similar to those described for a range of herbivorous, insectivorous and carnivorous marsupials. In the last quarter of lactation, however, brushtail possum milk maintained a relatively stable composition, with higher levels of carbohydrate and lower levels of lipid than for other marsupials. There appears to be a uniform pattern of changes in milk composition throughout the Marsupialia over most of lactation, with family differences evident only in the latter stages.
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Nagy, KA. "Seasonal Water, Energy and Food Use by Free-Living, Arid-Habitat Mammals." Australian Journal of Zoology 42, no. 1 (1994): 55. http://dx.doi.org/10.1071/zo9940055.
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In arid ecosystems, the dry season is probably an especially challenging time for animals to find adequate food and water resources. Both stressful and benevolent times of the year can be identified by measuring rates of water and energy use (with doubly labelled water), diet and behaviour throughout a year in free-ranging animals. Such field studies have been completed on four species of arid-land mammals. Jackrabbits (Lepus californicus) are strict herbivores, and most Mojave Desert individuals have no access to drinking water, and depend on their food for their water. When vegetation dries up during the summer drought, most jackrabbits apparently die of dehydration and malnutrition, but populations are replenished by bountiful reproduction after winter rains. However, springbok antelope (Antidorcas marsupialis), also strict herbivores, can maintain water and energy balance throughout the year in the Kalahari in southern Africa by drinking water if available, but, if not, they obtain enough water from dietary plants, probably by feeding before dawn, when food items have taken up water from the humid air. Antelope ground squirrels (Ammospermophilus leucurus) are omnivorous in the Mojave Desert, and are active diurnally. They have lower water and energy requirements than non-desert mammals of the same body mass, like many desert mammals, but their ability to find succulent plant or animal foods in all seasons appears to be their primary survival tool. On the other hand, Merriam's kangaroo rats (Dipodomys merriami) are essentially nocturnal, and were thought to be strict granivores that never drank. A recent study, done throughout a year in the Mojave Desert, confirms their lack of drinking, but reveals that they eat much green vegetation in late winter and spring, probably in connection with reproduction. They obtain additional water throughout the year by caching dry seeds in humid burrows, where seeds take up water hygroscopically before being eaten. Although springbok, antelope ground squirrels and Merriam's kangaroo rats were in negative energy and water balance at times during the year, only jackrabbits were severely stressed by the dry season. Each species has a unique suite of desert survival mechanisms. Future research should include carnivores as well as arid-habitat marsupials.
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Taggart, D. A., D. Schultz, and P. D. Temple-Smith. "Development and Application of Assisted Reproductive Technologies in Marsupials: Their Value for Conservation of Rock-wallabies." Australian Mammalogy 19, no. 2 (1996): 183. http://dx.doi.org/10.1071/am97183.
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Assisted reproductive technology is used routinely in management to treat infertility and in domestic species in basic husbandry. In eutherian mammals application of this technology is also well established in wildlife conservation programs. The development and application of this technology in marsupials, however, is a relatively new field. The reproductive techniques currently available for marsupial studies, their benefits and implications for conservation are discussed in order to remove any previous misconceptions and provide an insight into how these techniques might be applied. The potential of this technology for maintaining genetic variability and enhancing reproductive output of threatened marsupial species is highlighted, with particular reference to the conservation of rock wallabies.
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Woolley, PA. "Reproductive Pattern of Captive Boullanger Island Dibbers, Parantechinus apicalis (Marsupialia : Dasyuridae)." Wildlife Research 18, no. 2 (1991): 157. http://dx.doi.org/10.1071/wr9910157.
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The recent discovery in Western Australia of two island populations of the dibbler, Parantechinus apicalis, which is rare on the mainland, has provided an opportunity for further study of this species. Following the finding that all males in an island population died soon after the mating period in March, in contrast to mainland males which survive beyond their first breeding season in both the field and the laboratory, a study of the pattern of reproduction in captive island dibblers was made. Like mainland dibblers, island females were found to be monoestrous, and island males potentially capable of breeding in more than one season. Island dibblers are smaller than mainland dibblers but the estimated length of pseudopregnancy was found to be similar. The results of the study on captive island dibblers, together with observations made on the island population at the time it was discovered, suggest that the 'die-off' of males observed in each of the three years following their discovery may not be an inevitable event, as it is for the males of some other species of small dasyurid marsupials (e.g. Antechinus).
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Hughes, R. Leon. "Structure of the female reproductive tract of an adult parous Tasmanian tiger, Thylacinus cynocephalus." Australian Journal of Zoology 48, no. 5 (2000): 487. http://dx.doi.org/10.1071/zo00022.
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The present observations on the now-extinct Thylacinus are based on the reproductive system of an adult thylacine discovered among the specimens of the Hill collection at the Hubrecht Laboratory in the Netherlands. As in other marsupials, the reproductive tract was characterised by the presence of a uterus duplex and a vaginal complex where the ureters passed dorsally over each lateral vaginal canal to enter the bladder. The lateral vaginal canals each entered a urogenital sinus that terminated in a shallow cloaca. The gross dimensions of the reproductive tract of the thylacine were greater than those of any extant dasyurid marsupial. The distance from the rostral pole of the ovaries to the most caudal extremity of the urogenital sinus measured 25 cm. The distinctive aspects of the reproductive tract included a disproportionate enlargement of the corpus uteri that is without parallel in any other marsupial species. The bodies of the right and left uteri measured 10.4 cm 1.2 cm 0.9 cm and 9.1 cm 0.8 cm 0.7 cm respectively. The rostro-caudal length of the right and left cervices measured 2.7 cm and 1.7 cm respectively. The cervical canals entered the vaginal complex by way of a thick median vaginal septum. The elongated caudal component of the vaginal culs-de-sac lacked a median vaginal septum. As in other dasyurid marsupials, the lateral vaginae and associated vaginal complex were of diminutive proportions in relation to the typical marsupial pattern. The histology of the tract was remarkably good for tissue preserved since 1902 and indicated that the tissues were free of pathological changes. A characteristic marsupial pattern of ovarian folliculogenesis was evident where all but a thin peripheral zone of the cytoplasm of the primary oocyte became vacuolated during the pre-antral stage of ovarian follicle development.
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Coelho, Rafael Damasceno Fernandes, Raul Fernandes Dantas Sales, and Leonardo Barros Ribeiro. "Sexual dimorphism, diet, and notes on reproduction in Oxyrhopus trigeminus (Serpentes: Colubridae) in the semiarid Caatinga of northeastern Brazil." Phyllomedusa: Journal of Herpetology 18, no. 1 (June 18, 2019): 89–96. http://dx.doi.org/10.11606/issn.2316-9079.v18i1p89-96.
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Sexual dimorphism, diet, and notes on reproduction in Oxyrhopus trigeminus (Serpentes: Colubridae) in the semiarid Caatinga of northeastern Brazil. Selected morphological characters, diet, and reproduction of the false-coral snake, Oxyrhopus trigeminus, from several localities in the Caatinga region of northeastern Brazil are described based on examination of preserved specimens. Sexual dimorphism is evident, with females attaining larger body sizes than males, but males have relatively larger heads and tails. A total of 25 prey items was identifed in 23 of the 97 O. trigeminus examined; based on the orientation of the prey in the stomachs, all items were ingested headfrst. Lizards are the most frequent prey (96%) of O. trigeminus, with the lizard Tropidurus hispidus being the most important prey species both in number and in volume; marsupials account for 4% of the diet. Juveniles have a narrower dietary niche width than adults, presumably because they have smaller mouths with a narrower gape. Females have a wider dietary niche than males, but there is a high niche overlap between the sexes; males and females do not differ in prey volumes. The analysis of the gonads showed that 10 females have 4–13 vitellogenic follicles (mean 7.8 ± 2.8 follicles), and 2 females have oviducal eggs, one with only one egg and the other with fve eggs. The estimated minimum size at maturity for female O. trigeminus in the Caatinga is 400 mm.
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Körtner, Gerhard, Alexander Riek, Chris R. Pavey, and Fritz Geiser. "Activity patterns and torpor in two free-ranging carnivorous marsupials in arid Australia in relation to precipitation, reproduction, and ground cover." Journal of Mammalogy 97, no. 6 (July 15, 2016): 1555–64. http://dx.doi.org/10.1093/jmammal/gyw113.
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Moore, HD. "Gamete biology of the new world marsupial, the grey short-tailed opossum, Monodelphis domestica." Reproduction, Fertility and Development 8, no. 4 (1996): 605. http://dx.doi.org/10.1071/rd9960605.
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Mammalian gametes undergo a series of functional and developmental changes that culminate in fertilization. In order to appreciate the necessity for such complex processes as sperm maturation, capacitation and the intimate sperm-egg interactions leading to gamete fusion, it is important to understand how gametes may have evolved. In this respect, marsupials are particularly relevant since they exhibit features reminiscent of both non-mammalian vertebrates and eutherian mammals. The grey short-tailed opossum, Monodelphis domestica, is a New World marsupial from Brazil. It breeds well under laboratory conditions and is an excellent animal model to investigate marsupial gamete biology. As in other American marsupials, the spermatozoa of the opossum form pairs in the epididymis. Here, a number of studies carried out in this laboratory, related to sperm maturation, capacitation and fertilization in M. domestica, are reviewed and the gamete biology in this species is compared with what is known in other marsupials and eutherian mammals.
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Deakin, Janine E., and Sally Potter. "Marsupial chromosomics: bridging the gap between genomes and chromosomes." Reproduction, Fertility and Development 31, no. 7 (2019): 1189. http://dx.doi.org/10.1071/rd18201.
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Marsupials have unique features that make them particularly interesting to study, and sequencing of marsupial genomes is helping to understand their evolution. A decade ago, it was a huge feat to sequence the first marsupial genome. Now, the advances in sequencing technology have made the sequencing of many more marsupial genomes possible. However, the DNA sequence is only one component of the structures it is packaged into: chromosomes. Knowing the arrangement of the DNA sequence on each chromosome is essential for a genome assembly to be used to its full potential. The importance of combining sequence information with cytogenetics has previously been demonstrated for rapidly evolving regions of the genome, such as the sex chromosomes, as well as for reconstructing the ancestral marsupial karyotype and understanding the chromosome rearrangements involved in the Tasmanian devil facial tumour disease. Despite the recent advances in sequencing technology assisting in genome assembly, physical anchoring of the sequence to chromosomes is required to achieve a chromosome-level assembly. Once chromosome-level assemblies are achieved for more marsupials, we will be able to investigate changes in the packaging and interactions between chromosomes to gain an understanding of the role genome architecture has played during marsupial evolution.
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Isaac, Joanne L., and Christopher N. Johnson. "Terminal reproductive effort in a marsupial." Biology Letters 1, no. 3 (June 28, 2005): 271–75. http://dx.doi.org/10.1098/rsbl.2005.0326.
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Life-history theory predicts that as organisms approach the end of their life, they should increase their reproductive effort (RE). However, studies on mammals often find that measures of RE do not vary with maternal age. This might be because offspring have some control over energy transfer which may constrain adaptive variation in RE by mothers, particularly in eutherian mammals where placental function is primarily controlled by offspring. However, in marsupials, energy transfer is primarily by lactation and under maternal control, leaving marsupial mothers free to vary RE. Here, we provide the first analysis, to our knowledge, of age-specific RE in a marsupial, the common brushtail possum. RE, measured as the proportion of maternal mass lost during lactation, was strongly correlated with offspring mass as a yearling. Older females had higher RE, gave birth earlier in the season and were more likely to produce two offspring in a year. Females with high RE in one year were lighter at the beginning of the next breeding season. These results provide the clearest support yet for terminal RE in a mammal.
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Guilhon, Gabby Neves, Caryne Braga, and João Alves De Oliveira. "Pelage variation and reproduction in the gray short-tailed opossum Monodelphis domestica (Didelphimorphia: Didelphidae)." Journal of Mammalogy 100, no. 4 (June 3, 2019): 1364–73. http://dx.doi.org/10.1093/jmammal/gyz080.
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Abstract Marsupials have short gestation periods, with altricial neonates completing their development attached to a teat, a condition that induces remarkable structural changes in the inguinal region of reproductive females. In this study, we analyzed the morphological variation in the inguinal region of female museum specimens of Monodelphis domestica in search for external traits reminiscent of their reproductive condition when collected. We examined 427 taxidermied skins of wild females from northeastern Brazil and classified their inguinal region by color, density of fur, shape, and the presence of spots and teats. We determined relative age based on tooth eruption and wear, to infer the chronological order of inguinal changes. These conditions were computed for each age class and for each month over 4 years for samples from two mesoregions in northeastern Brazil, identified from climatic characteristics. Four distinct morphological patterns recognized in the inguinal region of females were associated with the following reproductive conditions: 1) non-lactating: general shape of the pelvic region indistinct from the rest of body (straight), inguinal region lacking teats, same fur density and color (grayish) as the rest of the body; 2) pre-lactating: pelvic and inguinal regions similar to non-lactating, but yellowish fur and presence of small teats; 3) early-lactating: inguinal region with well-developed teats, fur yellowish (rarely whitish) and less dense, and form of the pelvic region rounded; and 4) late or post-lactating: inguinal region with well-developed teats and dark orange and less dense fur, pelvic region rounded. Lactating females were only recorded from age class 4 on. We also found indications that pelage changes in the inguinal region do not revert after reproduction in the wild. Monthly frequencies of the different conditions recorded for lactating females corroborate previous studies that suggested that M. domestica breeds all year long in northeastern Brazil. Marsupiais caracterizam-se por apresentar um curto período de gestação, com neonatos altriciais completando seu desenvolvimento ligados à teta, uma condição que induz mudanças estruturais marcantes na região inguinal de fêmeas reprodutivas. No presente estudo analisamos a variação morfológica da região inguinal de fêmeas taxidermizadas de Monodelphis domestica, buscando traços reminiscentes de suas condições reprodutivas quando coletadas. Examinamos 427 peles taxidermizadas de fêmeas silvestres obtidas no Nordeste do Brasil, e classificamos a região inguinal pela cor, densidade de pelos, presença de manchas e tetas, e forma da região pélvica. Determinamos a idade relativa com base na erupção e no desgaste dentário, para inferir a ordem cronológica das mudanças inguinais. Essas condições foram registradas para cada idade e por cada mês ao longo de 4 anos para amostras de duas mesorregiões no Nordeste do Brasil, identificadas com base em características climáticas. Quatro padrões morfológicos distintos reconhecidos na região inguinal das fêmeas foram associadas às seguintes condições reprodutivas: 1) não-lactante: forma geral da região pélvica indistinta do resto do corpo (retas), região inguinal sem tetas e mesma cor e densidade da pelagem (cinza) que o resto do corpo; 2) pré-lactante: regiões inguinal e pélvica similares às do padrão não-lactante, mas pelagem amarelada e presença de tetas pequenas; 3) lactante inicial: região inguinal com tetas bem desenvolvidas, pelagem inguinal amarelada (raramente branca) e menos densa, forma da região pélvica arredondada; 4) lactante tardia ou pós-lactante: região inguinal com tetas bem desenvolvidas, pelagem laranja escura e menos densa, região pélvica arredondada. Fêmeas lactantes foram observadas apenas da classe de idade 4 em diante. Encontramos evidências de que a mudança da pelagem na região inguinal não é revertida depois da reprodução na natureza. Frequências mensais das diferentes condições reprodutivas das fêmeas observadas corroboram estudos prévios que sugerem que M. domestica pode se reproduzir ao longo de todo o ano no Nordeste do Brasil.
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Chen, Xiaolin, Chris R. Dickman, and Michael B. Thompson. "Diet of the mulgara, Dasycercus cristicauda (Marsupialia : Dasyuridae), in the Simpson Desert, central Australia." Wildlife Research 25, no. 3 (1998): 233. http://dx.doi.org/10.1071/wr97087.
Full textAbstract:
The diet of the mulgara, Dasycercus cristicauda, from the Simpson Desert in Queensland, was analysed using scats collected between 1990 and 1995. Insects, arachnids and rodents were the main classes of prey of D. cristicauda, but reptiles, centipedes and small marsupials were also consumed. Insects represented 92% by percentage frequency of occurrence in scats, while rodents represented 33% by percentage frequency. Invertebrate prey ≥6 mm in length and vertebrate prey occurred frequently in scats, but small prey ( 1–5 mm), when present, occurred in large numbers. D. cristicauda ate more individual prey items in spring and winter than in autumn, and more large-sized prey in spring than in autumn. In autumn, D. cristicauda consumed mostly insects (100% by frequency) and few rodents (8%), but in winter and spring, switched to rodents (38% and 47% respectively) and insects (88% and 93% respectively). Seasonal shifts in diet may reflect changes in the availability of different groups of prey, or changes in prey selectivity by D. cristicauda in response to costs imposed by seasonal reproduction. The dietary flexibility of D. cristicauda may allow individuals to occupy stable ranges, and has perhaps also promoted the persistence of the species in arid areas that have been subjected to changes in land use since European settlement.
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Renfree, M. B., S. R. Frankenberg, and C. Freyer. "054. TROPHOBLAST, PLACENTA AND EARLY EMBRYO: HOW THE MARSUPIAL DEVELOPS." Reproduction, Fertility and Development 22, no. 9 (2010): 15. http://dx.doi.org/10.1071/srb10abs054.
Full textAbstract:
In marsupials, the blastocyst forms as a single cell layer of cells. The marsupial blastocyst has no inner cell mass, so the 80–100 cell tammar embryo remains in diapause as a unilaminar blastocyst. All marsupials have a unilaminar stage, but what is unusual is that in the tammar the total cessation of cell division and cell metabolism lasts for 11 months each year. Marsupials are placental mammals. The yolk sac forms the definitive placenta up to birth. Only very few marsupials, such as the bandicoot, have a chorio-allantoic placenta, which supplements the placental functions of the yolk sac. However, the understanding how the unilaminar layer of trophoblast cells of the diapausing blastocyst become specified into placental and embryonic tissues has been an ongoing puzzle. To identify genes that do become differentially expressed in tammar development, we targeted the stage of the earliest appearance of the embryonic disc, at which the remainder of the blastocyst is then defined as trophoblast, as well as early cleavage stages. Intriguingly, we found no evidence for early differential expression of the canonical pluripotency genes POU5F1, SOX2 and NANOG, or of CDX2. By contrast, we found overt differential expression of GATA3, the closely related gene GATA2, and FGF4. This expression profile suggests that in the tammar, mechanisms regulating trophoblast- and pluriblast-specific expression of POU5F1, SOX2, NANOG and CDX2 are temporally secondary to those regulating GATA2 & -3 and FGF4 expression. Together, our results may signify the evolution of alternative mechanisms of early lineage specification in marsupials, or alternatively reveal a general hierarchy of signalling mechanisms that are masked in the relatively rapid and ‘compressed’ development of mice. The results of our ongoing study have important implications for understanding not only marsupial stem cells but the early development of all therian mammals.
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Yu, Hongshi, Andrew J. Pask, Yanqiu Hu, Geoff Shaw, and Marilyn B. Renfree. "ARX/Arx is expressed in germ cells during spermatogenesis in both marsupial and mouse." REPRODUCTION 147, no. 3 (March 2014): 279–89. http://dx.doi.org/10.1530/rep-13-0361.
Full textAbstract:
The X-linked aristaless gene,ARX, is essential for the development of the gonads, forebrain, olfactory bulb, pancreas, and skeletal muscle in mice and humans. Mutations cause neurological diseases, often accompanied by ambiguous genitalia. There are a disproportionately high number of testis and brain genes on the human and mouse X chromosomes. It is still unknown whether the X chromosome accrued these genes during its evolution or whether genes that find themselves on the X chromosome evolve such roles.ARXwas originally autosomal in mammals and remains so in marsupials, whereas in eutherian mammals it translocated to the X chromosome. In this study, we examined autosomalARXin tammars and compared it with the X-linkedArxin mice. We detectedARXmRNA in the neural cells of the forebrain, midbrain and hindbrain, and olfactory bulbs in developing tammars, consistent with the expression in mice.ARXwas detected by RT-PCR and mRNAin situhybridization in the developing tammar wallaby gonads of both sexes, suggestive of a role in sexual development as in mice. We also detectedARX/ArxmRNA in the adult testis in both tammars and mice, suggesting a potential novel role forARX/Arxin spermiogenesis.ARXtranscripts were predominantly observed in round spermatids.ArxmRNA localization distributions in the mouse adult testis suggest that it escaped meiotic sex chromosome inactivation during spermatogenesis. Our findings suggest thatARXin the therian mammal ancestor already played a role in male reproduction before it was recruited to the X chromosome in eutherians.
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Shevlyuk, N. N., and M. F. Ryskulov. "Seminal Vesicles and Bulbourethral Glands of Mammals: Morphology, Physiology, Ecology, Action of Extreme Destabilizing Factors." Journal of Anatomy and Histopathology 10, no. 3 (September 20, 2021): 98–107. http://dx.doi.org/10.18499/2225-7357-2021-10-3-98-107.
Full textAbstract:
In mammals, the adnexal sex glands are represented by seminal vesicles, the prostate gland, urethral and bulbourethral glands, as well as glands that coagulate sperm and ampullary glands. The secret of the accessory genital glands increases the volume of the ejaculate (the share of secretions of these glands accounts for about 95% of the volume of ejaculate) promotes sperm, causes increased contraction of smooth muscle cells in the walls of the female genital tract.The purpose of this review is to analyze the morphofunctional organization of seminal vesicles and bulbourethral glands of mammalian animals and humans.The presence or absence of seminal vesicles is a species-specific feature. Among mammals, seminal vesicles are well developed in some rodents, insectivores, a number of domestic animals (cattle, pigs), and primates. These glands are absent in cloacae, marsupials, some carnivores, a number of insectivores, artiodactyls. Bulbourethral glands are well developed in rodents, bats, primates, and some ungulates.In the wall of the seminal vesicles, the mucous, muscular and outer membranes are isolated. The epithelium of the secretory parts is pseudomultitial, the interstitium is represented by loose fibrous connective tissue and a significant number of smooth muscle cells. In the wall of the bulbourethral glands, the mucosa and adventitial membrane are isolated. The secretory end sections of the bulbourethral glands are lined with a single-layer single-row epithelium, glandular cells produce a mucosal or mixed secret. The seminal vesicles and bulbourethral glands are androgen-dependent glands. In species with a seasonal pattern of reproduction, their morphofunctional characteristics undergo significant changes during the circannual rhythm of reproduction.The epithelium of seminal vesicles and bulbourethral glands is very sensitive to the action of various adverse factors (heavy metal compounds, organic xenobiotics, electromagnetic radiation, ultrasound, etc.). When exposed to various negative factors in the adnexal glands, a complex of changes occurs (edema of connective tissue and epithelium, decreased secretory activity of epithelial cells, desynchronization of the secretory cycle, desquamation of glandular epithelial cells, proliferation of interstitial connective tissue).There is a lack of information on many aspects of the characteristics of the adnexal glands of the male reproductive system, primarily on the morphology and physiology of the adnexal glands of animals in natural ecosystems, on the ultrastructural and immunohistochemical characteristics of these glands, as well as on the mechanisms of regulation of morphofunctional rearrangements of the adnexal glands during seasonal reproduction rhythms, in the conditions of adaptation to various negative influences.