Auswahl der wissenschaftlichen Literatur zum Thema „Intra-fertility“

Women without a partner can become single mothers by choice through the use of fertility treatments. In Belgium, the decision to accept a candidate single mother by choice rests with the fertility clinic’s multidisciplinary team of fertility practitioners. As a result, the fertility practitioners fulfil a gatekeeping role. However, this can cause an intra-role conflict as the responsibility to select the best fitting candidates is at odds with the responsibility to help patients. In this explorative study, we examine how fertility practitioners cope with the strain resulting from intra-role conflict in the decision-making process regarding single motherhood by choice in Belgium. The findings showed that practitioners appear to mainly resort to problem-focused coping, by constructing a grassroots criteria list and by shifting their role from screening agent to counsellor. These results are based on ten open in-depth interviews with fertility practitioners employed in the multidisciplinary teams of fertility centers, using a reflexive interview lead.

A recent universal public health problem, intrauterine mortality (IUM), is probably the least documented demographic and social phenomenon in Morocco caused by data scarcity. This study aims to measure the IUM’s intensity and effect on women’s fertility. IUM quotients and their components (early fetal and late fetal mortality) were estimated by constructing the mortality table. An empirical examination of IUM’s impact on fertility was conducted using a direct method, the Bongaarts model (1978) and Leridon (2002) method. The data is from the 2009–2010 National Demographic Survey. The results show that in 2009–2010, the IUM quotient reached 272% pregnancies: 290% in urban areas versus 251% in rural areas. This IUM reduced potential fertility by 6% using the direct method. In particular, abortion reduced potential fertility by 5% versus 3.5% in 2009–2010, using the Bongaarts and Leridon methods. Given the importance of abortion, its impact on fertility, and its multidimensional consequences, it is interesting to research the determinants associated with the recourse to abortion as a significant public health issue.

SummaryThis report examines the implications of female genital cutting and other intra-vaginal practices for offering the TwoDay Method® of family planning. This fertility awareness-based method relies on the identification of cervico-vaginal secretions to identify the fertile window. Female genital cutting and traditional vaginal practices, such as the use of desiccants, may affect the presence or absence of secretions and therefore the woman's perception of her fertility. These issues and their implications for service delivery of the method are discussed.

In many human societies, high male social status associates with higher fertility, but the means by which status increases lifetime fitness have not been systematically investigated. We analyse the pathways by which male status begets reproductive success in a small-scale, Amerindian society. Men who are more likely to win a dyadic physical confrontation, i.e. dominant men, have higher intra-marital fertility for their age, and men with more community-wide influence, i.e. prestigious men, exhibit both higher intra-marital fertility and lower offspring mortality. Both forms of status elicit support from allies and deference from competitors, but high status men are not provisioned more than their peers. Prestigious but not dominant men marry wives who first give birth at earlier ages, which multivariate analysis suggests is the strongest pathway between status and fitness in this population. Furthermore, men are motivated to pursue status because of fitness gains both within and outside of marital unions: dominant and prestigious men have more in-pair surviving offspring as well as more extra-marital affairs.

Abstract The fertility potential of human sperm populations can be assessed by the presence of head-directed mannose ligand receptors (mannose-specific lectin) and the occurrence of spontaneous acrosome reactions after incubation under capacitating conditions in vitro. We have reported previously on the interaction between anti-hypertensive medications and their effects on these parameters of male fertility potential. In this report we document the effects of cessation of calcium ion channel blocker medication on male fertility. Motile spermatozoa from a 30 year old infertile patient on a calcium ion channel blocker as anti-hypertensive treatment had subnormal expression of mannose-specific lectin and did not exhibit spontaneous acrosome reactions. Three months following discontinuation of the medications, complete recovery of both the expression of head-directed mannose ligand receptors and the acrosome reaction was documented, though sperm motility and morphology remained unchanged. The couple had 2 years of infertility and previously failed to conceive through seven cycles of Pergonal/intra-uterine insemination. Conception occurred on the second Pergonal/intra-uterine insemination cycle after the husband discontinued calcium ion channel blocker medication. Calcium ion channel blockers may adversely affect sperm fertilizing potential. Discontinuation of such medications enhances the chances for conception.

This thesis focuses on the edible fungus Lepista (Pied Bleu or Wood Blewit). Factors affecting its potential commercial cultivation were explored and a contribution to knowledge of the morphology and cultivation of Australian species of Lepista has been made. Australian collections of Lepista were made within a 200 km zone of Sydney. A study of the morphology and taxonomic species of these collections was undertaken. Intra- and inter-fertility crosses were completed with French L. nuda and L. sordida to determine genetic relationships and biological species. Suitable substrates for agar medium, spawn production and cultivation were explored. The response to temperature of French and Australian Lepista in vitro, and Australian Lepista under cultivation, using cold shock, was observed. The effect of modified atmosphere exchanges per hour, CO2 levels, and cold shock during the cultivation cycle and sporophore production were investigated. A genebank of Australian Lepista was established. Three species of Lepista were found in Australia : L. nuda, L. sordida and L. saeva. Two other groups of Lepista were identified. The use of A. bisporus compost appeared to be optimal for experimental and commercial applications. Australian isolates of Lepista tolerate higher temperatures than French isolates, and grew at double the rate of the French at all temperatures except 5 degrees centigrade. The length of the spawn run was reduced from 43-58 days to 12-16 days with introduced CO2 of 9,000-11,000 ppm, but an erratic cyclic pattern of net CO2 production occurred which could only be stabilised by increasing ventilation. This initial cyclic pattern appeared to inhibit subsequent sporophore formation.
Doctor of Philosophy (PhD)

This thesis focuses on the edible fungus Lepista (Pied Bleu or Wood Blewit). Factors affecting its potential commercial cultivation were explored and a contribution to knowledge of the morphology and cultivation of Australian species of Lepista has been made. Australian collections of Lepista were made within a 200 km zone of Sydney. A study of the morphology and taxonomic species of these collections was undertaken. Intra- and inter-fertility crosses were completed with French L. nuda and L. sordida to determine genetic relationships and biological species. Suitable substrates for agar medium, spawn production and cultivation were explored. The response to temperature of French and Australian Lepista in vitro, and Australian Lepista under cultivation, using cold shock, was observed. The effect of modified atmosphere exchanges per hour, CO2 levels, and cold shock during the cultivation cycle and sporophore production were investigated. A genebank of Australian Lepista was established. Three species of Lepista were found in Australia : L. nuda, L. sordida and L. saeva. Two other groups of Lepista were identified. The use of A. bisporus compost appeared to be optimal for experimental and commercial applications. Australian isolates of Lepista tolerate higher temperatures than French isolates, and grew at double the rate of the French at all temperatures except 5 degrees centigrade. The length of the spawn run was reduced from 43-58 days to 12-16 days with introduced CO2 of 9,000-11,000 ppm, but an erratic cyclic pattern of net CO2 production occurred which could only be stabilised by increasing ventilation. This initial cyclic pattern appeared to inhibit subsequent sporophore formation.

L'objectif de ce projet repose sur le développement d’un dispositif médical intra-utérin résorbable prévenant l’apparition ou la récidive d'adhérences intra-utérines (synéchies). La mise en place de ce dispositif suite à chaque agréssion endométriale représenterait un bénéfice symptômatique et économique dans la prise en charge de l’infertilité par trouble de l'implantation. Ce dispositif repose sur l'association originale de polymères résorbables mis sous forme de films stérilisés et maléables, répondants aux contraintes spécifiques de la voie endo-utérine. Des tests sur culture cellulaire ont permis de valider son potentiel anti-adhérentiel en retrouvant des résultats comparables à ceux d’agents barrières disponibles sur le marché. La dégradation in vitro et in vivo du polymère a été étudiée afin de valider un délai d’efficacité suffisant. Des travaux expérimentaux ont été conduits après accord des comités d’éthiques. D’une part, des tests de reproduction animale ont été menés afin de démontrer l’innocuité du dispositif et son efficacité sur la fertilité. D’autre part, des travaux ont permis de valider sur le plan histologique l’effet préventif sur les synéchies. Un travail de modélisation a permis d’adapter la forme du film pour la voie utérine. Les tests de déploiement ont été conduits sur des utérus de cadavre et sur des pièces d’hystérectomie. Après mise en place aisée par les voies naturelles, le dispositif se déploie et gonfle afin de recouvrir la cavité utérine. Des travaux précliniques pourraient être envisagés avant un développement industriel afin d’améliorer les outils disponibles pour la prévention des synéchies intra-utérines
The objective of this study was to develop an resorbable intra-uterine medical device preventing the appearance or the recurrence of intra-uterine adhesions (synechiaes). The insertion of the device following each endometrial injury would represent a symptomatic and economic benefit in the treatment of infertility by implantation failure. This device is base on the unique combination of resorbables polymers formed into sterilized and malleable films, respondents to the specific constraints of the endo-uterine way. Cellular assays allowed validating the anti-adhesive effect with results comparable to those of currents agents available for the clinical practice. The in vitro and in vivo degradation of the polymer was study to validate a sufficient period of efficiency. The use of experimental models allowed an evaluation of the polymer. On one hand, tests of animal reproduction were lead to demonstrate the harmlessness of the device and the efficiency on the fertility. On the other hand, work has validated histologically preventive effect on synechiaes. Finally, a modeling work allowed adapting the form and dimension of the film for the human uterine way. Tests of deployment carried out on fresh uterus from hysterectomy. After the insertion by the cervical way, the device unfolds and inflates to cover the uterine cavity. Preclinical studies could be done before an industrial development in order to improve the available tools for the clinical prevention of the intra-uterine synechiaes

Le chapitre 1 évalue l'impact d'une politique publique au Pérou visant à améliorer l'accès à la justice et à réduire la violence contre les femmes. Ce chapitre utilise des données sur les centres de justice pour femmes (CJF) au Pérou, des institutions spécialisées qui emploient principalement des femmes et fournissent des services de police et des services juridiques pour réduire la violence fondée sur le genre. En examinant le déploiement progressif des CJF dans les districts, nous constatons que l'ouverture d'un centre augmente de 40 % le nombre de signalements de crimes spécifiques au genre et réduit d'environ 10 % l'incidence de la violence fondée sur le genre, mesurée par la violence domestique, les féminicides et les hospitalisations pour cause de santé mentale. Nous constatons en outre qu'une diminution de l'exposition des femmes à la violence domestique a des effets intergénérationnels : les CJF augmentent considérablement les investissements en capital humain pour les enfants, ce qui augmente la scolarisation, la présence scolaire et les résultats aux examens. Le chapitre 2 examine l'effet de la fécondité sur les décisions des parents albanais en matière d'offre de travail. Afin d'aborder la question de l'endogénéité potentielle de la décision de fécondité, j'exploite la préférence des parents albanais pour avoir des garçons combinés avec l'instrument de composition du genre des frères et sœurs comme source exogène de variation. En utilisant un échantillon représentatif de parents ayant au moins deux enfants, je constate un effet positif et significatif de la fécondité sur l'offre de travail pour les parents plus jeunes, moins scolarisés ou vivant dans une famille élargie. Les estimations pour les mères montrent qu'elles augmentent l'offre de travail en termes d'heures travaillées et de probabilité de travailler hors secteur rural. De même, la probabilité pour le père de travailler hors secteur rural et d'avoir un deuxième emploi augmente à la suite d'autres naissances. L'analyse de l'hétérogénéité suggère deux mécanismes plausibles : les services de garde offerts par des adultes non-parentaux (grands-parents) dans les familles élargies et les coûts financiers plus élevés liés au maintien d'un plus grand nombre d'enfants. Le chapitre 3 analyse l'effet du déplacement forcé de populations sur l'offre de travail des adultes et la scolarisation des enfants dans le contexte de l'après-guerre au Kosovo. Ce chapitre utilise la guerre du Kosovo de 1998-1999 et les déplacements massifs de population comme une expérimentation naturelle afin d'estimer l'impact du déplacement forcé dû au conflit sur les Kosovars qui sont partis et qui ont décidé de revenir par rapport à ceux qui sont restés pendant la guerre. J'exploite l'intéraction de la variation spatiale de l'intensité du conflit - mesurée par le nombre de victimes et de bombardements - et de la distance à la frontière albanaise comme source de variation exogène dans le statut de déplacement. Les résultats indiquent que les hommes kosovars déplacés sont moins susceptibles d'être employés dans le secteur agricole et de travailler pour leur propre compte, tandis que les femmes kosovares déplacées sont plus susceptibles d'être inactives. La perte d'actifs (terres, bétail, etc.) dans une économie agraire fondée sur les compétences et la perte de réseaux sociaux dans un marché du travail informel pourraient avoir réduit davantage la probabilité de trouver un emploi par rapport aux personnes qui sont restées. Toutefois, peu après le retour au pays, les résultats indiquent également que les hommes et les femmes kosovars déplacés sont plus susceptibles de travailler hors secteur rural, en particulier dans les secteurs de la construction et de l'administration publique, ce qui indique une reprise relativement rapide. En outre, les filles kosovares déplacées sont plus susceptibles d'être inscrites à l'école primaire, mais je ne constate aucun effet sur la scolarisation des garçons
Chapter 1 evaluates the impact of a policy intervention in Peru aimed at improving access to justice and reducing violence against women. In many developing countries, access to justice remains unequal, especially for women. What are the implications of this inequality for gender-based violence, intra-household bargaining, and investment in children? This paper provides evidence from Peru on all-women's justice centers (WJCs), specialized institutions that mostly employ female officers and provide police and legal services to reduce gender-based violence. Examining the gradual rollout of WJCs across districts/ villages, we find that the opening of a center increases reporting of gender-specific crimes by 40% and reduces the incidence of gender-based violence measured by domestic violence, femicides and hospitalizations due to mental health by about 10%. We find, moreover, that a decrease in the exposure of women to violence has intergenerational effects: WJCs substantially increase human capital investments in children, raising enrollment, attendance, and test scores. These results are consistent with a bargaining model in which women's access to justice determines the threat point. Chapter 2 examines the effect of fertility on labor supply decisions of Albanian parents, with particular attention to the intervening role of childcare provided by grandparents in extended families. In order to address the potential endogeneity in the fertility decision, I exploit Albanian parental preference for having sons combined with the sibling’s sex-composition instrument as an exogenous source of variation. Using a repeated cross-section of parents with at least two children, I find a positive and statistically significant effect of fertility on parental labor supply for those parents who are more likely to be younger, less educated or live in extended families. In particular, IV estimates for mothers show that they increase labor supply, especially in terms of hours worked per week and the likelihood of working off-farm. Similarly, father’s likelihood of working off-farm and having a second occupation increase as a consequence of further childbearing. The heterogeneity analysis suggests that this positive effect might be the result of two plausible mechanisms: childcare provided by non-parental adults in extended families and greater financial costs of maintaining more children. Chapter 3 analyzes the effect of forced displacement on adult’s labor market outcomes and children’s schooling in the context of the post-war Kosovo. This chapter uses the 1998-1999 Kosovo war and the following massive displacement of people as a natural experiment in order to estimate the impact of conflict displacement on Kosovars that left and decided to come back relative to those who stayed in the province. I exploit the interaction of the spatial variation in conflict intensity -as measured by casualties and bombings- and distance to the Albanian border as a source of exogenous variation in the displacement status. Results indicate that displaced Kosovar men are less likely to be employed in the agricultural sector and to work on their own account, while displaced Kosovar women are more likely to be inactive. Loss of assets (e.g. land, livestock) in an agrarian skill-based economy and also loss of social networks in an informal labor market might have further decreased the probability to find employment relative to stayers. However, shortly after the return home, the results also indicate that displaced Kosovar men and women are more likely to be working off-farm, especially in the construction and public administration sectors, which indicates a relatively quick recovery. In addition, displaced Kosovar girls are more likely to be enrolled in primary school, but I find no effect on education for boys. The refugee camp experience might have provided better conditions to young Kosovar girls compared to the precarious pre-war “parallel" education system

AbstractThe human species is biologically distinguished by low fertility. In fact, with each menstrual cycle, a couple at the peak of their reproductive capacity has only about a 30% chance of conceiving. The WHO states infertility as “a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected intercourse.”Assisted reproductive technology (ART) consists of all treatments or procedures that include the in vitro handling of both human oocytes and sperm or of embryos, for the purpose of establishing a pregnancy.The techniques are usually divided into three broad categories: First level techniques: Intrauterine and Intracervical Insemination (IUI/ICI), the simpler and less invasive ones, such as intrauterine insemination (IUI) with or without Intracervical Insemination (ICI) ovarian stimulation. Second level techniques: the more complex and more invasive ones that can be performed under local anesthesia or deep sedation, which differ from the basic techniques as they involve manipulation of female and male gametes and because they require in vitro fertilization. Among these techniques the IVF (In Vitro Fertilization and Embryo Transfer), ICSI (Intracytoplasmic Sperm Injection), and the possible cryopreservation of male and female gametes and embryos. Third level techniques procedures that require general anesthesia with intubation, including: laparoscopic egg retrieval, intra-tubal transfer of male and female gametes (GIFT), zygotes (ZIFT) and /or embryos (TET) laparoscopically; microsurgical sampling of gametes from the testicle: Testicular Sperm Extraction (TESE), Microsurgical Testicular Sperm Extraction (microTESE), Testicular Sperm Aspiration (TESA); microsurgical sampling of gametes from the epididymides: Percutaneous Epididymal Sperm Aspiration (PESA) and Microsurgical Epididymal Sperm Aspiration (MESA). In all assisted reproduction techniques, the seminal fluid receives a treatment able to induce capacitation “in vitro” so that the activated spermatozoa, at the threshold of the acrosomal reaction, can interact with the mature oocytes. Preimplantation Genetic Screening (PGS) and Preimplantation Genetic Diagnosis (PGD) are highly specialized procedures which involve removing three to four cells from a 5–6 day old blastocyst and testing them for chromosomal abnormalities prior to transferring the embryo into a woman’s uterus. According to data reported from the European IVF-Monitoring Consortium (EIM) for the European Society of Human Reproduction and Embryology (ESHRE), the clinical pregnancy rates (PR) per aspiration and per transfer are 28.0% and 34.8%, respectively. After ICSI, the corresponding rates are 24% and 33.5%. ART can alleviate the burden of infertility on individuals and families, but it can also present challenges to public health as evidenced by the high rates of multiple delivery, preterm delivery, and low birth-weight delivery experienced with ART.

This chapter begins with the principles of contraception (choice, access, measures of effectiveness) and a risk/benefit analysis and eligibility of different types. It explains emergency contraception. The chapter goes on to discuss different formulations, preparations, methods of use (or administration and insertion). This includes the combined oral contraceptive pill (COCOP), the transdermal patch, intra vaginal rings, progestogen-only pills, the subdermal implant, injectables, intra-uterine devices and systems, barrier methods for both male and female use, and spermicides. Finally it covers fertility awareness, and the sterilization of women and men.

Since the mid-1960s, India has experienced several notable shifts in its population dynamics that will have social implications for decades to come. This paper first sketches some of the central parameters of a complex picture that is characterised by regional and intra-regional contrasts. The main body of the paper considers the likely impact of these demographic processes by addressing the following themes: whether India is likely to benefit from the ‘demographic dividend’ derived from declining fertility; whether declining fertility combined with sex selective abortion might result in a ‘marriage squeeze’ that disadvantages young men and results in a decline in the significance of dowry payments; whether low fertility will impact positively on gender politics (including women’s access to employment and their position within their marital homes); and the implications of an increasingly ageing population for the intergenerational contract.

The article presents the results of using elements of coordinate farming technology that allow assessing productivity in fertility zones and differentially influencing the identified intra-field heterogeneity of the field, in order to increase the yield and economic efficiency of corn for grain, when it is cultivated in production conditions

Introduction: Immature teratoma represents 3% of all teratomas, 1 % of all ovarian cancers and 20% of malignant ovarian germ cell tumors. It is found either in pure form or as a component of a mixed germ cell tumor. It occurs essentially during the first two decades of life. According to WHO, immature teratoma is defined as a teratoma containing a variable amount of immature embryonal type neuroectodermal tissue Case: We present here a report of 23 years old unmarried female who presented with complaint of abdominal pain since 1 month and her CT scan done outside, showed fibroid uterus. She had history of typhoid fever 1 month back for which USG was done which suggested large uterine fibroid. On examination she was hemodynamically stable. On abdominal examination a non-tender supra-pubic mass of 24 weeks size with firm consistency, irregular margin was felt. On investigation CA 125 was 64.90 IU/L, LD- 223, beta HCG- 1.14. On MRI a large abdomino-pelvic lesion, likely left adnexal lesion with multiple cystic areas, with hemorrhage, with ascites and enlarged retroperitoneal lymph nodes with omental infiltration suggestive of a possibility of malignant germ cell tumor. In view of large ovarian tumor, possibly malignant decision for staging laparotomy was taken. Intra-operatively a large irregular vascular solid mass of 20 x 20 cms with bosselated appearance with few cystic lesions over it was seen, arising from left ovary and was sent for frozen section which reported malignant mature teratoma with components of immature teratoma. She underwent laparotomy with left salpingo-oophorectomy with right ovarian biopsy, omentectomy, appendectomy with B/L pelvic lymphadenectomy. Histopathology was suggestive of grade III immature teratoma. In view of grade III immature teratoma, she received chemotherapy (BEP regimen) post-operatively and is currently under follow up. Conclusion: This case reflects the importance of early diagnosis in cases of pelvic masses in young females. Fertility preservation should be considered in young women with germ cell tumors. Patients with grade II or III tumors or a mere advanced stage disease should be treated with adjuvant chemotherapy (BEP) in addition to surgery.

Abstract Mitochondria are the site of respiration and numerous other metabolic processes required for plant growth and development. Increased demands for metabolic energy are observed during different stages in the plants life cycle, but are particularly ample during germination and reproductive organ development. These activities are dependent upon the tight regulation of the expression and accumulation of various organellar proteins. Plant mitochondria contain their own genomes (mtDNA), which encode for rRNAs, tRNAs and some mitochondrial proteins. Although all mitochondria have probably evolved from a common alpha-proteobacterial ancestor, notable genomic reorganizations have occurred in the mtDNAs of different eukaryotic lineages. Plant mtDNAs are notably larger and more variable in size (ranging from 70~11,000 kbp in size) than the mrDNAs in higher animals (16~19 kbp). Another unique feature of plant mitochondria includes the presence of both circular and linear DNA fragments, which undergo intra- and intermolecular recombination. DNA-seq data indicate that such recombination events result with diverged mitochondrial genome configurations, even within a single plant species. One common plant phenotype that emerges as a consequence of altered mtDNA configuration is cytoplasmic male sterility CMS (i.e. reduced production of functional pollen). The maternally-inherited male sterility phenotype is highly valuable agriculturally. CMS forces the production of F1 hybrids, particularly in predominantly self-pollinating crops, resulting in enhanced crop growth and productivity through heterosis (i.e. hybrid vigor or outbreeding enhancement). CMS lines have been implemented in some cereal and vegetables, but most crops still lack a CMS system. This work focuses on the analysis of the molecular basis of CMS. We also aim to induce nuclear or organellar induced male-sterility in plants, and to develop a novel approach for fertility restoration. Our work focuses on Brassicaceae, a large family of flowering plants that includes Arabidopsis thaliana, a key model organism in plant sciences, as well as many crops of major economic importance (e.g., broccoli, cauliflower, cabbage, and various seeds for oil production). In spite of the genomic rearrangements in the mtDNAs of plants, the number of genes and the coding sequences are conserved among different mtDNAs in angiosperms (i.e. ~60 genes encoding different tRNAs, rRNAs, ribosomal proteins and subunits of the respiratory system). Yet, in addition to the known genes, plant mtDNAs also harbor numerous ORFs, most of which are not conserved among species and are currently of unknown function. Remarkably, and relevant to our study, CMS in plants is primarily associated with the expression of novel chimericORFs, which likely derive from recombination events within the mtDNAs. Whereas the CMS loci are localized to the mtDNAs, the factors that restore fertility (Rfs) are identified as nuclear-encoded RNA-binding proteins. Interestingly, nearly all of the Rf’s are identified as pentatricopeptide repeat (PPR) proteins, a large family of modular RNA-binding proteins that mediate several aspects of gene expression primarily in plant organelles. In this project we proposed to develop a system to test the ability of mtORFs in plants, which are closely related to known CMS factors. We will induce male fertility in various species of Brassicaceae, and test whether a down-relation in the expression of the recombinantCMS-genes restores fertility, using synthetically designed PPR proteins.

The corpus luteum (CL) is a transient endocrine gland that has a vital role in the regulation of the estrous cycle, fertility and the maintenance of pregnancy. In the absence of appropriate support, such as occurs during maternal recognition of pregnancy, the CL will regress. Prostaglandin F2a (PGF) was first suggested as the physiological luteolysin in ruminants several decades ago. Yet, the cellular mechanisms by which PGF causes luteal regression remain poorly defined. In recent years it became evident that the process of luteal regression requires a close cooperation between steroidogenic, endothelial and immune cells, all resident cells of this gland. Changes in the population of these cells within the CL closely consort with the functional changes occurring during various stages of CL life span. The proposal aimed to gain a better understanding of the intra-ovarian regulation of luteolysis and focuses especially on the possible reasons causing the early CL (before day 5) to be refractory to the luteolytic actions of PGF. The specific aims of this proposal were to: determine if the refractoriness of the early CL to PGF is due to its inability to synthesize or respond to endothelin–1 (ET-1), determine the cellular localization of ET, PGF and tumor necrosis factor a (TNF a) receptors in early and mid luteal phases, determine the functional relationships among ET-1 and cytokines, and characterize the effects of PGF and ET-1 on prostaglandin production by luteal cell types. We found that in contrast to the mature CL, administration of PGF2a before day 5 of the bovine cycle failed to elevate ET-1, ETA receptors or to induce luteolysis. In fact, PGF₂ₐ prevented the upregulation of the ET-1 gene by ET-1 or TNFa in cultured luteal cells from day 4 CL. In addition, we reported that ECE-1 expression was elevated during the transitionof the CL from early to mid luteal phase and was accompanied by a significant rise in ET-1 peptide. This coincides with the time point at which the CL gains its responsiveness to PGF2a, suggesting that ability to synthesize ET-1 may be a prerequisite for luteolysis. We have shown that while ET-1 mRNA was exclusively localized to endothelial cells both in young and mature CL, ECE-1 was present in the endothelial cells and steroidogenic cells alike. We also found that the gene for TNF receptor I is only moderately affected by the cytokines tested, but that the gene for TNF receptor II is upregulated by ET-1 and PGF₂ₐ. However, these cytokines both increase expression of MCP-1, although TNFa is even more effective in this regard. In addition, we found that proteins involved in the transport and metabolism of PGF (PGT, PGDH, COX-2) change as the estrous cycle progresses, and could contribute to the refractoriness of young CL. The data obtained in this work illustrate ET-1 synthesis throughout the bovine cycle and provide a better understanding of the mechanisms regulating luteal regression and unravel reasons causing the CL to be refractory to PGF2a.