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Artigos de revistas sobre o tema "Germ cells"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 27 de julho de 2024

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1

Kerr, Candace, John Gearhart, Aaron Elliott e Peter Donovan. "Embryonic Germ Cells: When Germ Cells Become Stem Cells". Seminars in Reproductive Medicine 24, n.º 5 (novembro de 2006): 304–13. http://dx.doi.org/10.1055/s-2006-952152.

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2

Wylie, Chris. "Germ Cells". Cell 96, n.º 2 (janeiro de 1999): 165–74. http://dx.doi.org/10.1016/s0092-8674(00)80557-7.

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3

Wylie, Chris. "Germ cells". Current Opinion in Genetics & Development 10, n.º 4 (agosto de 2000): 410–13. http://dx.doi.org/10.1016/s0959-437x(00)00105-2.

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4

Rossant, Janet. "Immortal germ cells?" Current Biology 3, n.º 1 (janeiro de 1993): 47–49. http://dx.doi.org/10.1016/0960-9822(93)90148-h.

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5

Xu, HongYan, MingYou Li, JianFang Gui e YunHan Hong. "Fish germ cells". Science China Life Sciences 53, n.º 4 (abril de 2010): 435–46. http://dx.doi.org/10.1007/s11427-010-0058-8.

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6

Wylie, Chris. "Introduction: Germ cells". Seminars in Developmental Biology 4, n.º 3 (junho de 1993): 147–48. http://dx.doi.org/10.1006/sedb.1993.1017.

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7

Eppig, John, e Mary Ann Handel. "Germ Cells from Stem Cells". Biology of Reproduction 79, n.º 1 (1 de julho de 2008): 172–78. http://dx.doi.org/10.1095/biolreprod.108.070789.

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8

Schulz, Cordula, Cricket G. Wood, D. Leanne Jones, Salli I. Tazuke e Margaret T. Fuller. "Signaling from germ cells mediated by therhomboidhomologstetorganizes encapsulation by somatic support cells". Development 129, n.º 19 (1 de outubro de 2002): 4523–34. http://dx.doi.org/10.1242/dev.129.19.4523.

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Germ cells normally differentiate in the context of encapsulating somatic cells. However, the mechanisms that set up the special relationship between germ cells and somatic support cells and the signals that mediate the crucial communications between the two cell types are poorly understood. We show that interactions between germ cells and somatic support cells in Drosophila depend on wild-type function of the stet gene. In males, stet acts in germ cells to allow their encapsulation by somatic cyst cells and is required for germ cell differentiation. In females, stet function allows inner sheath cells to enclose early germ cells correctly at the tip of the germarium. stet encodes a homolog of rhomboid, a component of the epidermal growth factor receptor signaling pathway involved in ligand activation in the signaling cell. The stet mutant phenotype suggests that stet facilitates signaling from germ cells to the epidermal growth factor receptor on somatic cells, resulting in the encapsulation of germ cells by somatic support cells. The micro-environment provided by the surrounding somatic cells may, in turn, regulate differentiation of the germ cells they enclose.

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9

Zhangab, Rong, Wancun Chang e Jian-Yong Han. "Culture of Rabbit Embryonic Germ Cells Derived from Primordial Germ Cells". Journal of Applied Animal Research 26, n.º 2 (dezembro de 2004): 61–66. http://dx.doi.org/10.1080/09712119.2004.9706509.

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10

Stewart, Colin L., Inder Gadi e Harshida Bhatt. "Stem Cells from Primordial Germ Cells Can Reenter the Germ Line". Developmental Biology 161, n.º 2 (fevereiro de 1994): 626–28. http://dx.doi.org/10.1006/dbio.1994.1058.

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11

M, Yang. "In Vitro Germ Line Differentiation from Pluripotent Stem Cells". Journal of Embryology & Stem Cell Research 3, n.º 2 (2019): 1–3. http://dx.doi.org/10.23880/jes-16000126.

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12

Bajaj, Anubha. "Intramural and Adapted-Germ Cell Neoplasia In situ". Journal of Medical Case Studies 2, n.º 1 (2024): 1–4. http://dx.doi.org/10.23880/jmcs-16000115.

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Germ cell neoplasia in situ emerges as a precursor lesion configuring type II germ cell tumours as testicular seminoma or post-pubertal non-seminomatous testicular germ cell tumours. Lesion is comprised of neoplastic gonocyte-like cells, latent totipotent or naive germ cells with developmental potential situated within ‘spermatogonial niche’ of seminiferous tubules. Germ cell neoplasia in situ delineates an increased incidence with conditions as uncorrected cryptorchidism, ambiguous genitalia, infertility or preceding history of post-pubertal germ cell tumour within contralateral testis. Neoplasm demonstrates aneuploidy or polypoid genotype with additional chromosomal gains as is chromosome 12p upon commencement of neoplastic invasion. Neoplastic cells appear enlarged, atypical, gonocyte-like and are incorporated with abundant, clear cytoplasm, enlarged, hyper chromatic nuclei, coarse nuclear chromatin, angulated cellular margins and prominent nucleoli.

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13

Donovan, Peter J., e Maria P. de Miguel. "Turning germ cells into stem cells". Current Opinion in Genetics & Development 13, n.º 5 (outubro de 2003): 463–71. http://dx.doi.org/10.1016/j.gde.2003.08.010.

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14

Vielle-Calzada, Jean-Philippe. "Linking stem cells to germ cells". Science 356, n.º 6336 (27 de abril de 2017): 378–79. http://dx.doi.org/10.1126/science.aan2734.

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15

Samuel, Elizabeth Jeya Vardhini, Joseph Vimal, Nagarajan Natarajan, Sivakumar Periasamy, Sanjoy George e Gouthaman Thiruvenkadam. "Cancer and Germ Cells". Open Journal of Preventive Medicine 04, n.º 07 (2014): 606–15. http://dx.doi.org/10.4236/ojpm.2014.47070.

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16

McLaren, A. "Signaling for germ cells". Genes & Development 13, n.º 4 (15 de fevereiro de 1999): 373–76. http://dx.doi.org/10.1101/gad.13.4.373.

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17

Hines, Pamela J. "Germ cells on demand". Science 356, n.º 6336 (27 de abril de 2017): 392.11–394. http://dx.doi.org/10.1126/science.356.6336.392-k.

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18

López, A., N. Xamena, R. Marcos e A. Velázquez. "Germ cells microsatellite instability". Mutation Research/Genetic Toxicology and Environmental Mutagenesis 514, n.º 1-2 (fevereiro de 2002): 87–94. http://dx.doi.org/10.1016/s1383-5718(01)00325-4.

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19

Cinalli, Ryan M., Prashanth Rangan e Ruth Lehmann. "Germ Cells Are Forever". Cell 132, n.º 4 (fevereiro de 2008): 559–62. http://dx.doi.org/10.1016/j.cell.2008.02.003.

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20

Xu, Cong, Yu Li, Zhengshun Wen, Muhammad Jawad, Lang Gui e Mingyou Li. "Spinyhead Croaker Germ Cells Gene dnd Visualizes Primordial Germ Cells in Medaka". Life 12, n.º 8 (12 de agosto de 2022): 1226. http://dx.doi.org/10.3390/life12081226.

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Spinyhead croaker (Collichthys lucidus) is an economically important fish suffering from population decline caused by overfishing and habitat destruction. Researches on the development of primordial germ cell (PGC) and reproduction biology were an emergency for the long-term conservation of the involved species. Dead end (dnd) gene plays an indispensable role in PGC specification, maintenance, and development. In the current study, we report the cloning and expression patterns of dnd in C. lucidus (Cldnd). RT-PCR analysis revealed that Cldnd was specifically expressed in both sexual gonads. In the ovary, Cldnd RNA was uniformly distributed in the oocytes and abundant in oogonia, and gradually decreased with oogenesis. A similar expression pattern was also detected in testis. Dual fluorescent in situ hybridization of Cldnd and Clvasa demonstrated that they almost had the same distribution except in oocytes at stage I, in which the vasa RNA aggregated into some particles. Furthermore, Cldnd 3′ UTR was sufficient to guide the Green Fluorescent Protein (GFP) specifically and stably expressed in the PGCs of medaka. These findings offer insight into that Cldnd is an evolutionarily conserved germline-specific gene and even a potential candidate for PGC manipulation in C. lucidus.

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21

Horii, T. "Serum-free culture of murine primordial germ cells and embryonic germ cells". Theriogenology 59, n.º 5-6 (março de 2003): 1257–64. http://dx.doi.org/10.1016/s0093-691x(02)01166-4.

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22

Kimura, T., M. Tomooka, N. Yamano, K. Murayama, S. Matoba, H. Umehara, Y. Kanai e T. Nakano. "AKT signaling promotes derivation of embryonic germ cells from primordial germ cells". Development 135, n.º 5 (23 de janeiro de 2008): 869–79. http://dx.doi.org/10.1242/dev.013474.

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23

Robbins, H., C. Dores, K. Coyle e I. Dobrinski. "74 GERM CELLS AND TESTICULAR SOMATIC CELLS HAVE DIFFERENT SENSITIVITY TO CRYOPRESERVATION". Reproduction, Fertility and Development 25, n.º 1 (2013): 184. http://dx.doi.org/10.1071/rdv25n1ab74.

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Spermatogonial stem cells (SSC) are the foundation of spermatogenesis. Undifferentiated spermatogonia, containing SSC, represent only 2 to 5% of cells recovered from immature mammalian testis. Cryopreservation in liquid nitrogen allows for long-term storage of cells. Preservation of germ cells can serve as a means of genetic preservation from immature males when sperm storage is not an option. Studies have investigated the effects of cryopreservation on the spermatogenic potential of SSC and the efficiency of various cryopreservation protocols. Preliminary observations indicated that germ cells may survive cryopreservation better than testicular somatic cells, resulting in a post-thaw cell population enriched in germ cells. However, this has not been critically evaluated. The objective of this study was to test the hypothesis that germ cells are less susceptible to cryo-damage than testicular somatic cells. Cells were harvested from the testes of 1-wk-old piglets by 2-step enzymatic digestion. The initial cell suspension was subjected to differential adhesion to enrich the cell population for germ cells. Cells were plated in DMEM + 5% fetal bovine serum and incubated at 37°C in 5% CO2 in air. After 18 h, cells in suspension and cells slightly attached were recovered by trypsinization (1 : 10 trypsin-ethylenediaminetetraacetic acid) for 30 s and replated. This was repeated 24 and 36 h after initial plating. The enriched population was placed into cryovials at a concentration of 30 × 106 cells in freezing media (70% DMEM + 20% fetal bovine serum + 10% dimethyl sulfoxide), kept for 24 h at –80°C in a cryogenic freezing container and transferred to liquid nitrogen for 1 week. Aliquots of cells before freezing and after thawing at 37°C followed by incubation at 37°C in 5% CO2 in air for 1 h were analyzed for viability by propidium iodide (PI) exclusion and immunofluorescence for the germ cell marker VASA to identify viable germ cells (VASA+/PI–), nonviable germ cells (VASA+/PI+), viable somatic cells (VASA–/PI–), and nonviable somatic cells (VASA–/PI+). The percentage of viable germ cells after freezing and thawing was compared to the percentage of viable somatic cells by ANOVA. After enrichment by differential plating, the cell population had 95.6 ± 0.9% viability and contained 27.1 ± 7.4% germ cells (n = 3 replicates). After cryopreservation, the overall cell viability was 77.5 ± 1.6%, and 25.8 ± 8.0% were germ cells. The overall viability after cryopreservation could potentially have benefited from the 1-h incubation prior to analysis. The viability of the germ cell population after freezing and thawing was higher (92.1 ± 3.1%) than somatic cell viability (72.3 ± 1.7%; P < 0.01). These results indicate that porcine germ cells survive cryopreservation better than do testicular somatic cells. Therefore, cryostorage of germ cells can be an efficient means for preservation of male genetic material. Supported by NIH ORIP/DCM RR17359.

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24

Malekmohamadi, Nasim, Alireza Abdanipour, Mehrdad Ghorbanlou, Saeed Shokri, Reza Shirazi, Eva Dimitriadis e Reza Nejatbakhsh. "Differentiation of bone marrow derived mesenchymal stem cells into male germ-like cells in co-culture with testicular cells". Endocrine Regulations 53, n.º 2 (1 de abril de 2019): 93–99. http://dx.doi.org/10.2478/enr-2019-0011.

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AbstractObjective. Stem cell therapy, specifically, pre-induction of mesenchymal stem cells toward male germ-like cells may be useful in patients with azoospermia. The aim of this study was to evaluate in vitro differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs) into male germ-like cells by indirect co-culture with testicular cells in the presence of bone morphogenetic protein 4 (BMP4).Methods. Experimental groups included: control (mouse BMSCs), treatment group-1 (BMSCs treated with BMP4), treatment group-2 (indirect co-culture of BMSCs with mouse testicular cells in the presence of BMP4) and treatment group-3 (indirect co-culture of BMSCs with testicular cells). BMSCs-derived male germ-like cells were evaluated by the expression of Dazl, and Stra8 using RT-qPCR.Results. Stra8 gene expression was significantly increased in the treatment group-2 and Dazl gene was significantly increased in the treatment group-1 compared to other groups. In conclusion, indirect co-culturing of BMSCs with testicular cells and BMP4 leads to the differentiation of BMSCs into male germ-like cells which express specific male germ-like genes. Testicular cells released factors that contributed to the differentiation of BMSCs into male germ progenitor cells.Conclusion. This study suggests that mesenchymal stem cells may be differentiated into male germ-like cells and therefore, may be a novel treatment option for men with azoospermia.

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25

Hou, Jingmei, Shi Yang, Hao Yang, Yang Liu, Yun Liu, Yanan Hai, Zheng Chen et al. "Generation of male differentiated germ cells from various types of stem cells". REPRODUCTION 147, n.º 6 (junho de 2014): R179—R188. http://dx.doi.org/10.1530/rep-13-0649.

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Infertility is a major and largely incurable disease caused by disruption and loss of germ cells. It affects 10–15% of couples, and male factor accounts for half of the cases. To obtain human male germ cells ‘especially functional spermatids’ is essential for treating male infertility. Currently, much progress has been made on generating male germ cells, including spermatogonia, spermatocytes, and spermatids, from various types of stem cells. These germ cells can also be used in investigation of the pathology of male infertility. In this review, we focused on advances on obtaining male differentiated germ cells from different kinds of stem cells, with an emphasis on the embryonic stem (ES) cells, the induced pluripotent stem (iPS) cells, and spermatogonial stem cells (SSCs). We illustrated the generation of male differentiated germ cells from ES cells, iPS cells and SSCs, and we summarized the phenotype for these stem cells, spermatocytes and spermatids. Moreover, we address the differentiation potentials of ES cells, iPS cells and SSCs. We also highlight the advantages, disadvantages and concerns on derivation of the differentiated male germ cells from several types of stem cells. The ability of generating mature and functional male gametes from stem cells could enable us to understand the precise etiology of male infertility and offer an invaluable source of autologous male gametes for treating male infertility of azoospermia patients.

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26

Lehtiniemi, Tiina, e Noora Kotaja. "Germ granule-mediated RNA regulation in male germ cells". Reproduction 155, n.º 2 (fevereiro de 2018): R77—R91. http://dx.doi.org/10.1530/rep-17-0356.

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Germ cells have exceptionally diverse transcriptomes. Furthermore, the progress of spermatogenesis is accompanied by dramatic changes in gene expression patterns, the most drastic of them being near-to-complete transcriptional silencing during the final steps of differentiation. Therefore, accurate RNA regulatory mechanisms are critical for normal spermatogenesis. Cytoplasmic germ cell-specific ribonucleoprotein (RNP) granules, known as germ granules, participate in posttranscriptional regulation in developing male germ cells. Particularly, germ granules provide platforms for the PIWI-interacting RNA (piRNA) pathway and appear to be involved both in piRNA biogenesis and piRNA-targeted RNA degradation. Recently, other RNA regulatory mechanisms, such as the nonsense-mediated mRNA decay pathway have also been associated to germ granules providing new exciting insights into the function of germ granules. In this review article, we will summarize our current knowledge on the role of germ granules in the control of mammalian male germ cell’s transcriptome and in the maintenance of fertility.

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27

Nowak-Imialek, Monika, Wilfried Kues, Joseph W. Carnwath e Heiner Niemann. "Pluripotent Stem Cells and Reprogrammed Cells in Farm Animals". Microscopy and Microanalysis 17, n.º 4 (20 de junho de 2011): 474–97. http://dx.doi.org/10.1017/s1431927611000080.

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AbstractPluripotent cells are unique because of their ability to differentiate into the cell lineages forming the entire organism. True pluripotent stem cells with germ line contribution have been reported for mice and rats. Human pluripotent cells share numerous features of pluripotentiality, but confirmation of their in vivo capacity for germ line contribution is impossible due to ethical and legal restrictions. Progress toward derivation of embryonic stem cells from domestic species has been made, but the derived cells were not able to produce germ line chimeras and thus are termed embryonic stem-like cells. However, domestic animals, in particular the domestic pig (Sus scrofa), are excellent large animals models, in which the clinical potential of stem cell therapies can be studied. Reprogramming technologies for somatic cells, including somatic cell nuclear transfer, cell fusion, in vitro culture in the presence of cell extracts, in vitro conversion of adult unipotent spermatogonial stem cells into germ line derived pluripotent stem cells, and transduction with reprogramming factors have been developed with the goal of obtaining pluripotent, germ line competent stem cells from domestic animals. This review summarizes the present state of the art in the derivation and maintenance of pluripotent stem cells in domestic animals.

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28

Kurek, Magdalena, Halima Albalushi, Outi Hovatta e Jan-Bernd Stukenborg. "Human Pluripotent Stem Cells in Reproductive Science—A Comparison of Protocols Used to Generate and Define Male Germ Cells from Pluripotent Stem Cells". International Journal of Molecular Sciences 21, n.º 3 (4 de fevereiro de 2020): 1028. http://dx.doi.org/10.3390/ijms21031028.

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Globally, fertility-related issues affect around 15% of couples. In 20%–30% of cases men are solely responsible, and they contribute in around 50% of all cases. Hence, understanding of in vivo germ-cell specification and exploring different angles of fertility preservation and infertility intervention are considered hot topics nowadays, with special focus on the use of human pluripotent stem cells (hPSCs) as a source of in vitro germ-cell generation. However, the generation of male germ cells from hPSCs can currently be considered challenging, making a judgment on the real perspective of these innovative approaches difficult. Ever since the first spontaneous germ-cell differentiation studies, using human embryonic stem cells, various strategies, including specific co-cultures, gene over-expression, and addition of growth factors, have been applied for human germ-cell derivation. In line with the variety of differentiation methods, the outcomes have ranged from early and migratory primordial germ cells up to post-meiotic spermatids. This variety of culture approaches and cell lines makes comparisons between protocols difficult. Considering the diverse strategies and outcomes, we aim in this mini-review to summarize the literature regarding in vitro derivation of human male germ cells from hPSCs, while keeping a particular focus on the culture methods, growth factors, and cell lines used.

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29

Singhal, D. K., H. N. Malik, R. Singhal, S. Saugandhika, A. Dubey, S. Boateng, S. Kumar, J. K. Kaushik, A. K. Mohanty e D. Malakar. "199 GERM-CELL-LIKE CELLS GENERATION FROM GOAT INDUCED PLURIPOTENT STEM CELLS". Reproduction, Fertility and Development 26, n.º 1 (2014): 214. http://dx.doi.org/10.1071/rdv26n1ab199.

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Primordial germ cells (PGCs) generated from embryonic stem (ES) cells in different species may be an alternative approach to dealing with the worldwide problem of increasing female infertility. Reprogramming of fibroblasts into induced pluripotent stem cells has been achieved by overexpression of different transcription factors. Here, we report the generation of female goat germ cells from goat induced pluripotent stems cells (giPSC). Goat induced pluripotent stem cells (giPSC) were produced by transduction of adult female goat fibroblast cells with Oct4, Sox2, and Nanog lentiviral particles and further sub-cultured on fibroblast feeder layers. GiPSC were characterised by different methods. These iPSC were found to express alkaline phosphatase, SSEA1, SSEA4, Tra-1–81, and Tra-1–60 surface markers. However, SSEA3 was not observed in giPSC. GiPSC also expressed Oct4, Nanog, and Sox2. Along with Oct4, Nanog, and Sox2, the expression of different transcription factors such as Cdx1, Dapp5, Dax1, Ecat, Eras, Fgf4, Gata6, Lin28, Rex1, and Utf1 was confirmed by RT-PCR. GiPSC were in vitro differentiated and three germ layers were characterised by immunostaining of Gata4 for endoderm, α-Actinin for mesoderm, and β-III tubulin for ectoderm and RT-PCR analysis of GATA4, α-Actinin and BMP4. IPSCs were directed differentiated into germ cells using retinoic acid and bone morphogenetic protein 4 without the inactivation of exogenous factors as these are also required for germ cells development. Differentiated germ cells were characterised by immunostaining against VASA and Dazl proteins. RT–PCR assay was performed for Dazl, Nanog, Nanos1, PUM8, SCP3, Stella, and VASA genes expression. Quantitative PCR was also performed for detection of VASA and Dazl expression during the course of germ cell differentiation. Flow-cytometric analysis of differentiated germ cells was confirmed the presence of germ cells in population of differentiated giPSC. Oocytes/ova-like structures, which were comparable to natural goat oocytes, were observed under scanning electron microscope (SEM). Cumulus–oocyte complex like structure was observed, which was further used for SEM. The study concluded that adult female goat fibroblast cells can be reprogrammed into induced pluripotent stem cells using ectopic expression of Oct4, Nanog, and Sox2 genes and the germ-cells-like cells generated from reprogrammed giPSC could be differentiated into goat oocytes/ova-like structure which have immense applications in human and animal reproduction.

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30

Ge, W., C. Chen, M. De Felici e W. Shen. "In vitro differentiation of germ cells from stem cells: a comparison between primordial germ cells and in vitro derived primordial germ cell-like cells". Cell Death & Disease 6, n.º 10 (outubro de 2015): e1906-e1906. http://dx.doi.org/10.1038/cddis.2015.265.

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31

DuBuc, Timothy Q., Christine E. Schnitzler, Eleni Chrysostomou, Emma T. McMahon, Febrimarsa, James M. Gahan, Tara Buggie et al. "Transcription factor AP2 controls cnidarian germ cell induction". Science 367, n.º 6479 (13 de fevereiro de 2020): 757–62. http://dx.doi.org/10.1126/science.aay6782.

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Clonal animals do not sequester a germ line during embryogenesis. Instead, they have adult stem cells that contribute to somatic tissues or gametes. How germ fate is induced in these animals, and whether this process is related to bilaterian embryonic germline induction, is unknown. We show that transcription factor AP2 (Tfap2), a regulator of mammalian germ lines, acts to commit adult stem cells, known as i-cells, to the germ cell fate in the clonal cnidarian Hydractinia symbiolongicarpus. Tfap2 mutants lacked germ cells and gonads. Transplanted wild-type cells rescued gonad development but not germ cell induction in Tfap2 mutants. Forced expression of Tfap2 in i-cells converted them to germ cells. Therefore, Tfap2 is a regulator of germ cell commitment across germ line–sequestering and germ line–nonsequestering animals.

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32

VIGNON, Xavier, Solange DELASALLE, Jacques FLÉCHON e Yasuhisa MATSUI. "CHARACTERIZATION OF EMBRYONIC GERM CELLS DERIVED FROM PRIMORDIAL GERM CELLS IN THE MOUSE". Biology of the Cell 88, n.º 1-2 (1996): 79. http://dx.doi.org/10.1016/s0248-4900(97)86883-9.

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33

Steinmann-Zwicky, M. "Sex determination of the Drosophila germ line: tra and dsx control somatic inductive signals". Development 120, n.º 3 (1 de março de 1994): 707–16. http://dx.doi.org/10.1242/dev.120.3.707.

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In Drosophila, the sex of germ cells is determined by cell-autonomous and inductive signals. XY germ cells autonomously enter spermatogenesis when developing in a female host. In contrast, XX germ cells non-autonomously become spermatogenic when developing in a male host. In first instar larvae with two X chromosomes, XX germ cells enter the female or the male pathway depending on the presence or absence of transformer (tra) activity in the surrounding soma. In somatic cells, the product of tra regulates the expression of the gene double sex (dsx) which can form a male-specific or a female-specific product. In dsx mutant larvae, XX and XY germ cells develop abnormally, with a seemingly intersexual phenotype. This indicates that female-specific somatic dsx products feminize XX germ cells, and male-specific somatic dsx products masculinize XX and XY germ cells. The results show that tra and dsx control early inductive signals that determine the sex of XX germ cells and that somatic signals also affect the development of XY germ cells. XX germ cells that develop in pseudomales lacking the sex-determining function of Sxl are spermatogenic. If, however, female-specific tra functions are expressed in these animals, XX germ cells become oogenic. Furthermore, transplanted XX germ cells can become oogenic and form eggs in XY animals that express the female-specific function of tra. Therefore, TRA product present in somatic cells of XY animals or in animals lacking the sex-determining function of Sxl, is sufficient to support developing XX germ cells through oogenesis.

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Poirie, M., E. Niederer e M. Steinmann-Zwicky. "A sex-specific number of germ cells in embryonic gonads of Drosophila". Development 121, n.º 6 (1 de junho de 1995): 1867–73. http://dx.doi.org/10.1242/dev.121.6.1867.

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Male first instar larvae possess more germ cells in their gonads than female larvae of the same stage. To determine the earliest time point of sexual dimorphism in germ cell number, we have counted the germ cells of sexed embryos at different developmental stages. We found no difference in germ cell number of male and female embryos at the blastoderm and early gastrulation stage, or when germ cells are about to exit the midgut pocket. We find, however, that males have significantly more germ cells than females as soon as the germ cells are near the places where the gonads are formed and in all later stages. Our results show that germ cells are subject to a sex-specific control mechanism that regulates the number of germ cells already in embryos.

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35

Nayernia, Karim. "Germ cells, origin of somatic stem cells?" Cell Research 18, S1 (agosto de 2008): S26. http://dx.doi.org/10.1038/cr.2008.116.

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36

Ledger, Bill. "Germ cells from human embryonic stem cells?" Reproductive BioMedicine Online 29, n.º 3 (setembro de 2014): 273. http://dx.doi.org/10.1016/j.rbmo.2014.07.004.

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Fujita, K., A. Tsujimura e A. Okuyama. "Isolation of germ cells from leukemic cells". Human Reproduction 22, n.º 10 (25 de julho de 2007): 2796–97. http://dx.doi.org/10.1093/humrep/dem212.

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Griswold, Michael D. "50 years of spermatogenesis: Sertoli cells and their interactions with germ cells". Biology of Reproduction 99, n.º 1 (15 de fevereiro de 2018): 87–100. http://dx.doi.org/10.1093/biolre/ioy027.

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Abstract The complex morphology of the Sertoli cells and their interactions with germ cells has been a focus of investigators since they were first described by Enrico Sertoli. In the past 50 years, information on Sertoli cells has transcended morphology alone to become increasingly more focused on molecular questions. The goal of investigators has been to understand the role of the Sertoli cells in spermatogenesis and to apply that information to problems relating to male fertility. Sertoli cells are unique in that they are a nondividing cell population that is active for the reproductive lifetime of the animal and cyclically change morphology and gene expression. The numerous and distinctive junctional complexes and membrane specializations made by Sertoli cells provide a scaffold and environment for germ cell development. The increased focus of investigators on the molecular components and putative functions of testicular cells has resulted primarily from procedures that isolate specific cell types from the testicular milieu. Products of Sertoli cells that influence germ cell development and vice versa have been characterized from cultured cells and from the application of transgenic technologies. Germ cell transplantation has shown that the Sertoli cells respond to cues from germ cells with regard to developmental timing and has furthered a focus on spermatogenic stem cells and the stem cell niche. Very basic and universal features of spermatogenesis such as the cycle of the seminiferous epithelium and the spermatogenic wave are initiated by Sertoli cells and maintained by Sertoli-germ cell cooperation.

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Gonczy, P., e S. DiNardo. "The germ line regulates somatic cyst cell proliferation and fate during Drosophila spermatogenesis". Development 122, n.º 8 (1 de agosto de 1996): 2437–47. http://dx.doi.org/10.1242/dev.122.8.2437.

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Spermatogenesis relies on the function of germ-line stem cells, as a continuous supply of differentiated spermatids is produced throughout life. In Drosophila, there must also be somatic stem cells that produce the cyst cells that accompany germ cells throughout spermatogenesis. By lineage tracing, we demonstrate the existence of such somatic stem cells and confirm that of germ-line stem cells. The somatic stem cells likely correspond to the ultrastructurally described cyst progenitor cells. The stem cells for both the germ-line and cyst lineage are anchored around the hub of non-dividing somatic cells located at the testis tip. We then address whether germ cells regulate the behavior of somatic hub cells, cyst progenitors and their daughter cyst cells by analyzing cell proliferation and fate in testes in which the germ line has been genetically ablated. Daughter cyst cells, which normally withdraw from the cell cycle, continue to proliferate in the absence of germ cells. In addition, cells from the cyst lineage switch to the hub cell fate. Male-sterile alleles of chickadee and diaphanous, which are deficient in germ cells, exhibit similar cyst cell phenotypes. We conclude that signaling from germ cells regulates the proliferation and fate of cells in the somatic cyst lineage.

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Johnson, Andrew D., Brian Crother, Mary E. White, Roger Patient, Rosemary F. Bachvarova, Matthew Drum e Thomas Masi. "Regulative germ cell specification in axolotl embryos: a primitive trait conserved in the mammalian lineage". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 358, n.º 1436 (29 de agosto de 2003): 1371–79. http://dx.doi.org/10.1098/rstb.2003.1331.

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How germ cells are specified in the embryos of animals has been a mystery for decades. Unlike most developmental processes, which are highly conserved, embryos specify germ cells in very different ways. Curiously, in mouse embryos germ cells are specified by extracellular signals; they are not autonomously specified by maternal germ cell determinants (germ plasm), as are the germ cells in most animal model systems. We have developed the axolotl ( Ambystoma mexicanum ), a salamander, as an experimental system, because classic experiments have shown that the germ cells in this species are induced by extracellular signals in the absence of germ plasm. Here, we provide evidence that the germ cells in axolotls arise from naive mesoderm in response to simple inducing agents. In addition, by analysing the sequences of axolotl germ–cell–specific genes, we provide evidence that mice and urodele amphibians share a common mechanism of germ cell development that is ancestral to tetrapods. Our results imply that germ plasm, as found in species such as frogs and teleosts, is the result of convergent evolution. We discuss the evolutionary implications of our findings.

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Coffman, Clark R., Rachel C. Strohm, Fredrick D. Oakley, Yukiko Yamada, Danielle Przychodzin e Robert E. Boswell. "Identification of X-Linked Genes Required for Migration and Programmed Cell Death of Drosophila melanogaster Germ Cells". Genetics 162, n.º 1 (1 de setembro de 2002): 273–84. http://dx.doi.org/10.1093/genetics/162.1.273.

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Abstract Drosophila germ cells form at the posterior pole of the embryo and migrate to the somatic gonad. Approximately 50% of the germ cells that form reach their target. The errant cells within the embryo undergo developmentally regulated cell death. Prior studies have identified some autosomal genes that regulate germ cell migration, but the genes that control germ cell death are not known. To identify X-linked genes required for germ cell migration and/or death, we performed a screen for mutations that disrupt these processes. Here we report the identification of scattershot and outsiders, two genes that regulate the programmed death of germ cells. The scattershot gene is defined by a mutation that disrupts both germ cell migration and the death of germ cells ectopic to the gonad. Maternal and zygotic expression of scattershot is required, but the migration and cell death functions can be genetically uncoupled. Zygotic expression of wild-type scattershot rescues germ cell pathfinding, but does not restore the programmed death of errant cells. The outsiders gene is required zygotically. In outsiders mutant embryos, the appropriate number of germ cells is incorporated into the gonad, but germ cells ectopic to the gonad persist.

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Schüpbach, Trudi. "NORMAL FEMALE GERM CELL DIFFERENTIATION REQUIRES THE FEMALE X CHROMOSOME TO AUTOSOME RATIO AND EXPRESSION OF SEX-LETHAL IN DROSOPHILA MELANOGASTER". Genetics 109, n.º 3 (1 de março de 1985): 529–48. http://dx.doi.org/10.1093/genetics/109.3.529.

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ABSTRACT In somatic cells of Drosophila, the ratio of X chromosomes to autosomes (X:A ratio) determines sex and dosage compensation. The present paper addresses the question of whether germ cells also use the X:A ratio for sex determination and dosage compensation. Triploid female embryos were generated which, through the loss of an unstable ring-X chromosome, contained some germ cells of 2X;3A constitution in their ovaries. Such germ cells were shown to differentiate along one of two alternative pathways: a minority developed into normal female oocytes and eggs; the majority developed into abnormal multicellular cysts. An X:A ratio of 1 is, therefore, required in female germ cell development, at least in the mature ovary after stem cell division.—Abnormal development of female germ cells was also observed when 2X;2A germ cells which were homozygous or trans-heterozygous for mutant alleles at the Sex-lethal locus were transplanted into normal female host embryos at the blastoderm stage. Germ cells homozygous for amorphic alleles failed to give rise to normal eggs. Instead, they formed multicellular cysts, very similar to those formed by 2X;3A cells. Zygotic Sxl + activity is, therefore, also necessary for the development of normal female germ cells. No abnormalities were detected in transplanted germ cells from female embryos whose mothers had been homozygous for the mutation daughterless. When normal XY germ cells were transplanted into female embryos, no traces of such cells could be found in the adult ovary. XY germ cells seem, therefore, not to develop as far as 2X;3A or Sxl homozygous cells in a female gonad. This indicates that neither 2X;3A nor Sxl homozygous germ cells are equivalent to normal XY germ cells.

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Kadyk, Lisa C., Eric J. Lambie e Judith Kimble. "glp-3 Is Required for Mitosis and Meiosis in the Caenorhabditis elegans Germ Line". Genetics 145, n.º 1 (1 de janeiro de 1997): 111–21. http://dx.doi.org/10.1093/genetics/145.1.111.

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The germ line is the only tissue in Caenorhabditis elegans in which a stem cell population continues to divide mitotically throughout life; hence the cell cycles of the germ line and the soma are regulated differently. Here we report the genetic and phenotypic characterization of the glp-3 gene. In animals homozygous for each of five recessive loss-of-function alleles, germ cells in both hermaphrodites and males fail to progress through mitosis and meiosis, but somatic cells appear to divide normally. Germ cells in animals grown at 15° appear by DAPI staining to be uniformly arrested at the G2/M transition with <20 germ cells per gonad on average, suggesting a checkpoint-mediated arrest. In contrast, germ cells in mutant animals grown at 25° frequently proliferate slowly during adulthood, eventually forming small germ lines with several hundred germ cells. Nevertheless, cells in these small germ lines never undergo meiosis. Double mutant analysis with mutations in other genes affecting germ cell proliferation supports the idea that glp-3 may encode a gene product that is required for the mitotic and meiotic cell cycles in the C. elegans germ line.

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Gulimiheranmu, Maisumu, Xinjie Wang e Junmei Zhou. "Advances in Female Germ Cell Induction from Pluripotent Stem Cells". Stem Cells International 2021 (13 de janeiro de 2021): 1–13. http://dx.doi.org/10.1155/2021/8849230.

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Germ cells are capable of maintaining species continuity through passing genetic and epigenetic information across generations. Female germ cells mainly develop during the embryonic stage and pass through subsequent developmental stages including primordial germ cells, oogonia, and oocyte. However, due to the limitation of using early human embryos as in vivo research model, in vitro research models are needed to reveal the early developmental process and related mechanisms of female germ cells. After birth, the number of follicles gradually decreases with age. Various conditions which damage ovarian functions would cause premature ovarian failure. Alternative treatments to solve these problems need to be investigated. Germ cell differentiation from pluripotent stem cells in vitro can simulate early embryonic development of female germ cells and clarify unresolved issues during the development process. In addition, pluripotent stem cells could potentially provide promising applications for female fertility preservation after proper in vitro differentiation. Mouse female germ cells have been successfully reconstructed in vitro and delivered to live offspring. However, the derivation of functional human female germ cells has not been fully achieved due to technical limitations and ethical issues. To provide an updated and comprehensive information, this review centers on the major studies on the differentiation of mouse and human female germ cells from pluripotent stem cells and provides references to further studies of developmental mechanisms and potential therapeutic applications of female germ cells.

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Scotting, P. J. "Are cranial germ cell tumours really tumours of germ cells?" Neuropathology and Applied Neurobiology 32, n.º 6 (dezembro de 2006): 569–74. http://dx.doi.org/10.1111/j.1365-2990.2006.00797.x.

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Lehmann, Ruth H. "Germ Cells Are Forever: Programming of the Germ Line Genome." Biology of Reproduction 83, Suppl_1 (1 de novembro de 2010): 61. http://dx.doi.org/10.1093/biolreprod/83.s1.61.

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LE MAGUERESSE, B., C. PINEAU, F. GUILLOU e B. JEGOU. "INFLUENCE OF GERM CELLS UPON TRANSFERRIN SECRETION BY RAT SERTOLI CELLS in vitro". Journal of Endocrinology 118, n.º 3 (setembro de 1988): R13—R16. http://dx.doi.org/10.1677/joe.0.118r013.

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ABSTRACT Indirect approach (hypotonic treatment) and direct approaches (co-cultures and conditioned media) were used in order to investigate the effects of germ cells from adult rats upon transferrin secretion by Sertoli cell cultures prepared from 20-day-old rats. Removal of germ cells contaminating the Sertoli cell cultures resulted in a significant decrease in transferrin secretion whereas the addition of crude germ cell preparations or of enriched preparations of pachytene spermatocytes, early spermatids and of liver epithelial cells (LEC) markedly stimulated this parameter. Furthermore, spent media of pachytene spermatocytes and of early spermatids, but not of LEC, also stimulated transferrin production. It is concluded that germ cells normally located within the adluminal compartment of the seminiferous tubules may be capable of controlling their own supply of iron via their influence upon transferrin secretion by the Sertoli cells.

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Biermann, K., e K. Steger. "Epigenetics in Male Germ Cells". Journal of Andrology 28, n.º 4 (7 de fevereiro de 2007): 466–80. http://dx.doi.org/10.2164/jandrol.106.002048.

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Ariagno, J., S. Curi, G. Mendeluk, D. Grinspon, H. Repetto, P. Chenlo, N. Pugliese, M. Sardi e A. M. Blanco. "SHEDDING OF IMMATURE GERM CELLS". Archives of Andrology 48, n.º 2 (janeiro de 2002): 127–31. http://dx.doi.org/10.1080/014850102317267436.

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Carreau, Serge, Helene Bouraima-Lelong e Christelle Delalande. "Estrogens in male germ cells". Spermatogenesis 1, n.º 2 (abril de 2011): 90–94. http://dx.doi.org/10.4161/spmg.1.2.16766.

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