RESUMO
Infertility is one of the most prevalent health disorders in reproductive-age males and females. Ficus carica (Fc), an herbal plant, has been used traditionally for the treatment of different diseases such as infertility especially in Iranian folk medicine. This study examined the effects of Fc leaf extract on the proliferation of mice spermatogonial stem cells (SSCs). Phenolic, flavonoid content, major polyphenolic compounds and antioxidant activity of the extract was evaluated respectively by Folin-Ciocateu, aluminum chloride, HPLC and the FRAP and DPPH methods. Testicular cells of neonate mice were extracted and their identity was confirmed using cytokeratin for Sertoli and Oct-4, CDHI and PLZF for SSCs. Effects of Fc (0.0875, 0.175, 0.35, 0.71 and 1.42 mg/ml) was evaluated at third, 7th, 9th and 14th days of culture by colony assay. The expression of the Mvh, GFRα1 and Oct-4 genes and the viability and proliferation of cultured cells was assessed at the end of the culture period. The extract has a rich phenolic and flavonoid content such as Rutin, Psoralen, Bergapten and Caffeoylmalic acid using HPLC analysis. It also had a potent reducing and radical scavenging activity. Morphology of colonies was similar in all groups. Higher viability, proliferation, colony number and diameter of SSCs was seen in the presence of Fc leaf extract in a dose-dependent manner so that higher number and diameter of colonies were observed in two higher doses of 0.71 and 1.42 mg/ml, separately for each time point relative to other groups. The Mvh, Oct-4 and GFRα1 genes expression had no significant differences between groups. It seems that Fc leaf extract not only had no any cytotoxic effects on the viability and proliferation of SSCs but also support their stemness state. So, this culture system can be employed for enrichment of germ stem cells for use in clinical applications.
RESUMO
Glial cell line-derived neurotrophic factor (GDNF) and its receptor (GDNF Family Receptor α1-GFRα1) are well known to mediate spermatogonial stem cell (SSC) proliferation and survival in mammalian testes. In nonmammalian species, Gdnf and Gfrα1 orthologs have been found but their functions remain poorly investigated in the testes. Considering this background, this study aimed to understand the roles of the Gdnf-Gfrα1 signaling pathway in zebrafish testes by combining in vivo, in silico and ex vivo approaches. Our analysis showed that zebrafish exhibit two paralogs for Gndf (gdnfa and gdnfb) and its receptor, Gfrα1 (gfrα1a and gfrα1b), in accordance with a teleost-specific third round of whole genome duplication. Expression analysis further revealed that both ligands and receptors were expressed in zebrafish adult testes. Subsequently, we demonstrated that gdnfa is expressed in the germ cells, while Gfrα1a/Gfrα1b was detected in early spermatogonia (mainly in types Aund and Adiff) and Sertoli cells. Functional ex vivo analysis showed that Gdnf promoted the creation of new available niches by stimulating the proliferation of both type Aund spermatogonia and their surrounding Sertoli cells but without changing pou5f3 mRNA levels. Strikingly, Gdnf also inhibited late spermatogonial differentiation, as shown by the decrease in type B spermatogonia and down-regulation of dazl in a co-treatment with Fsh. Altogether, our data revealed that a germ cell-derived factor is involved in maintaining germ cell stemness through the creation of new available niches, supporting the development of spermatogonial cysts and inhibiting late spermatogonial differentiation in autocrine- and paracrine-dependent manners.
Assuntos
Fator Neurotrófico Derivado de Linhagem de Célula Glial , Peixe-Zebra , Animais , Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Masculino , Mamíferos/metabolismo , Espermatogônias/metabolismo , Nicho de Células-Tronco , Peixe-Zebra/metabolismoRESUMO
Infertility is one of the most prevalent health disorders in reproductive-age males and females. Ficus carica (Fc), an herbal plant, has been used traditionally for the treatment of different diseases such as infertility especially in Iranian folk medicine. This study examined the effects of Fc leaf extract on the proliferation of mice spermatogonial stem cells (SSCs). Phenolic, flavonoid content, major polyphenolic compounds and antioxidant activity of the extract was evaluated respectively by Folin-Ciocateu, aluminum chloride, HPLC and the FRAP and DPPH methods. Testicular cells of neonate mice were extracted and their identity was confirmed using cytokeratin for Sertoli and Oct-4, CDHI and PLZF for SSCs. Effects of Fc (0.0875, 0.175, 0.35, 0.71 and 1.42 mg/ml) was evaluated at third, 7th, 9th and 14th days of culture by colony assay. The expression of the Mvh, GFRα1 and Oct-4 genes and the viability and proliferation of cultured cells was assessed at the end of the culture period. The extract has a rich phenolic and flavonoid content such as Rutin, Psoralen, Bergapten and Caffeoylmalic acid using HPLC analysis. It also had a potent reducing and radical scavenging activity. Morphology of colonies was similar in all groups. Higher viability, proliferation, colony number and diameter of SSCs was seen in the presence of Fc leaf extract in a dosedependent manner so that higher number and diameter of colonies were observed in two higher doses of 0.71 and 1.42 mg/ml, separately for each time point relative to other groups. The Mvh, Oct-4 and GFRα1 genes expression had no significant differences between groups. It seems that Fc leaf extract not only had no any cytotoxic effects on the viability and proliferation of SSCs but also support their stemness state. So, this culture system can be employed for enrichment of germ stem cells for use in clinical applications.(AU)
Assuntos
Animais , Camundongos , Extratos Vegetais/efeitos adversos , Ficus/efeitos adversos , Camundongos/embriologia , Citotoxicidade Imunológica , Células-Tronco Germinativas Adultas/citologiaRESUMO
Collared peccaries (Tayassu tajacu) present a unique testis cytoarchitecture, where Leydig cells (LC) are mainly located in cords around the seminiferous tubules (ST) lobes. This peculiar arrangement is very useful to better investigate and understand the role of LC in spermatogonial stem cells (SSCs) biology and niche. Recent studies from our laboratory using adult peccaries have shown that the undifferentiated type A spermatogonia (Aund or SSCs) are preferentially located in ST regions adjacent to the intertubular compartment without LC. Following these studies, our aims were to investigate the collared peccary postnatal testis development, from birth to adulthood, with emphasis on the establishment of LC cytoarchitecture and the SSCs niche. Our findings demonstrated that the unique LC cytoarchitecture is already present in the neonate peccary's testis, indicating that this arrangement is established during fetal development. Based on the most advanced germ cell type present at each time period evaluated, puberty (the first sperm release in the ST lumen) in this species was reached at around one year of age, being preceded by high levels of estradiol and testosterone and the end of Sertoli cell proliferation. Almost all gonocytes and SSCs expressed Nanos1, Nanos2 and GFRA1. The analysis of SSCs preferential location indicated that the establishment of SSCs niche is coincident with the occurrence of puberty. Taken together, our findings reinforced and extended the importance of the collared peccary as an animal model to investigate testis function in mammals, particularly the aspects related to testis organogenesis and the SSCs biology and niche.
Assuntos
Artiodáctilos/crescimento & desenvolvimento , Biomarcadores/metabolismo , Espermatogônias/citologia , Nicho de Células-Tronco , Células-Tronco/metabolismo , Testículo/crescimento & desenvolvimento , Animais , Peso Corporal , Hormônios/metabolismo , Masculino , Tamanho do Órgão , Fenótipo , Túbulos Seminíferos/metabolismo , Células de Sertoli/metabolismo , Espermatogênese , Espermatogônias/metabolismo , Testículo/anatomia & histologia , Testículo/metabolismoRESUMO
Molecular mechanisms responsible for the initiation of primate spermatogenesis remain poorly characterized. Previously, 48 h stimulation of the testes of three juvenile rhesus monkeys with pulsatile LH and FSH resulted in down-regulation of a cohort of genes recognized to favor spermatogonia stem cell renewal. This change in genetic landscape occurred in concert with amplification of Sertoli cell proliferation and the commitment of undifferentiated spermatogonia to differentiate. In this report, the non-protein coding small RNA transcriptomes of the same testes were characterized using RNA sequencing: 537 mature micro-RNAs (miRNAs), 322 small nucleolar RNAs (snoRNAs) and 49 small nuclear RNAs (snRNAs) were identified. Pathway analysis of the 20 most highly expressed miRNAs suggested that these transcripts contribute to limiting the proliferation of the primate Sertoli cell during juvenile development. Gonadotrophin treatment resulted in differential expression of 35 miRNAs, 12 snoRNAs and four snRNA transcripts. Ten differentially expressed miRNAs were derived from the imprinted delta-like homolog 1-iodothyronine deiodinase 3 (DLK1-DIO3) locus that is linked to stem cell fate decisions. Four gonadotrophin-regulated expressed miRNAs were predicted to trigger a local increase in thyroid hormone activity within the juvenile testis. The latter finding leads us to predict that, in primates, a gonadotrophin-induced selective increase in testicular thyroid hormone activity, together with the established increase in androgen levels, at the onset of puberty is necessary for the normal timing of Sertoli cell maturation, and therefore initiation of spermatogenesis. Further examination of this hypothesis requires that peripubertal changes in thyroid hormone activity of the testis of a representative higher primate be determined empirically.
Assuntos
MicroRNAs/metabolismo , Testículo/metabolismo , Hormônios Tireóideos/metabolismo , Animais , Hormônio Foliculoestimulante/metabolismo , Hormônio Luteinizante/metabolismo , Macaca mulatta , Masculino , MicroRNAs/genética , Análise de Sequência de RNA , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Espermatogênese/genética , Espermatogênese/fisiologia , Transcriptoma/genéticaRESUMO
The establishment of proper conditions for spermatogonial stem cells (SSCs) cryopreservation and storage represents an important biotechnological approach for the preservation of the genetic stock of valuable animals. This study demonstrates the effects of different cryopreservation protocols on the survival rates and phenotypic expression of SSCs in horses. The cells were enzymatically isolated from testes of eight adult horses. After enrichment and characterization of germ cells in the suspension, the feasibility of several cryopreservation protocols were evaluated. Three different cryomedia compositions, associated with three different methods of freezing (vitrification, slow-freezing and fast-freezing) were evaluated. Based on the rates of viable SSCs found before and after thawing, as well as the number of recovered cells after cryopreservation, the best results were obtained utilizing the DMSO-based cryomedia associated with the slow-freezing method. In addition, when isolated cells were cultured in vitro, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and immunofluorescence analysis indicated that the cryopreserved cells were as metabolically active as the fresh cells and were also expressing typical SSCs proteins (VASA, NANOS2 and GFRA1). Therefore, our results indicate that equine SSCs can be cryopreserved without impairment of structure, function, or colony-forming abilities.
Assuntos
Células-Tronco Germinativas Adultas/citologia , Criopreservação/métodos , Preservação do Sêmen/métodos , Espermatogônias/citologia , Vitrificação , Animais , Sobrevivência Celular , Crioprotetores/farmacologia , Dimetil Sulfóxido/farmacologia , Cavalos , Masculino , Tecido Parenquimatoso/citologia , Testículo/citologiaRESUMO
The history of transgenesis is marked by milestones such as the development of cellular transdifferentiation, recombinant DNA, genetic modification of target cells, and finally, the generation of simpler genetically modified organisms (e.g. bacteria and mice). The first transgenic fish was developed in 1984, and since then, continuing technological advancements to improve gene transfer have led to more rapid, accurate, and efficient generation of transgenic animals. Among the established methods are microinjection, electroporation, lipofection, viral vectors, and gene targeting. Here, we review the history of animal transgenesis, with an emphasis on fish, in conjunction with major developments in genetic engineering over the past few decades. Importantly, spermatogonial stem cell modification and transplantation are two common techniques capable of revolutionizing the generation of transgenic fish. Furthermore, we discuss recent progress and future biotechnological prospects of fish transgenesis, which has strong applications for the aquaculture industry. Indeed, some transgenic fish are already available in the current market, validating continued efforts to improve economically important species with biotechnological advancements.
Assuntos
Animais Geneticamente Modificados/genética , Peixes/genética , Técnicas de Transferência de Genes/tendências , Animais , Aquicultura/tendênciasRESUMO
Busulfan is a chemotherapy drug that has side effects on spermatogonial stem cells (SSC). The effects of bulsufan treatment on male germ cells and fertility vary significantly between individuals. In this study, we have used molecular, cellular and histopathology approaches to investigate the effects of a single intraperitoneal dose of busulfan (40mgkg(-1)) in two mice strains, Balb/C and Swiss, at two different periods after treatment, 30 and 90 days. Testicular degeneration was observed in both Balb/C and Swiss mice after busulfan injection. Interestingly, testicular functions and fertility recovered spontaneously post busulfan treatment in Swiss mice, but not in Balb/C mice. Abnormal fertility induced by busulfan in Balb/C mice was associated with altered seminiferous tubules, sperm morphology and transcript levels of Nanos2, Nanos3, Gdnf and Plzf genes. These findings revealed that SSC of Balb/C mice are more sensitive to the toxic effects of busulfan then those of Swiss mice.
Assuntos
Antineoplásicos Alquilantes/toxicidade , Bussulfano/toxicidade , Fertilidade/efeitos dos fármacos , Infertilidade Masculina/induzido quimicamente , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacos , Animais , Forma Celular/efeitos dos fármacos , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Infertilidade Masculina/metabolismo , Infertilidade Masculina/patologia , Infertilidade Masculina/fisiopatologia , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Nascido Vivo , Masculino , Camundongos Endogâmicos BALB C , Gravidez , Proteína com Dedos de Zinco da Leucemia Promielocítica , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Especificidade da Espécie , Motilidade dos Espermatozoides/efeitos dos fármacos , Espermatozoides/patologia , Testículo/metabolismo , Testículo/patologiaRESUMO
Mammalian spermatogenesis is a complex process in which spermatogonial stem cells of the testis (SSCs) develop to ultimately form spermatozoa. In the seminiferous epithelium, SSCs self-renew to maintain the pool of stem cells throughout life, or they differentiate to generate a large number of germ cells. A balance between SSC self-renewal and differentiation is therefore essential to maintain normal spermatogenesis and fertility. Stem cell homeostasis is tightly regulated by signals from the surrounding microenvironment, or SSC niche. By physically supporting the SSCs and providing them with these extrinsic molecules, the Sertoli cell is the main component of the niche. Earlier studies have demonstrated that GDNF and CYP26B1, produced by Sertoli cells, are crucial for self-renewal of the SSC pool and maintenance of the undifferentiated state. Down-regulating the production of these molecules is therefore equally important to allow germ cell differentiation. We propose that NOTCH signaling in Sertoli cells is a crucial regulator of germ cell fate by counteracting these stimulatory factors to maintain stem cell homeostasis. Dysregulation of this essential niche component can lead by itself to sterility or facilitate testicular cancer development.(AU)
Assuntos
Animais , Masculino , Células-Tronco/química , Células Germinativas/enzimologia , HomeostaseRESUMO
Mammalian spermatogenesis is a complex process in which spermatogonial stem cells of the testis (SSCs) develop to ultimately form spermatozoa. In the seminiferous epithelium, SSCs self-renew to maintain the pool of stem cells throughout life, or they differentiate to generate a large number of germ cells. A balance between SSC self-renewal and differentiation is therefore essential to maintain normal spermatogenesis and fertility. Stem cell homeostasis is tightly regulated by signals from the surrounding microenvironment, or SSC niche. By physically supporting the SSCs and providing them with these extrinsic molecules, the Sertoli cell is the main component of the niche. Earlier studies have demonstrated that GDNF and CYP26B1, produced by Sertoli cells, are crucial for self-renewal of the SSC pool and maintenance of the undifferentiated state. Down-regulating the production of these molecules is therefore equally important to allow germ cell differentiation. We propose that NOTCH signaling in Sertoli cells is a crucial regulator of germ cell fate by counteracting these stimulatory factors to maintain stem cell homeostasis. Dysregulation of this essential niche component can lead by itself to sterility or facilitate testicular cancer development.
Assuntos
Masculino , Animais , Células Germinativas/enzimologia , Células-Tronco/química , HomeostaseRESUMO
Approximately 0.2% of Americans aged 20 to 39 years are childhood cancer survivors. Advances in cancer detection and therapy have greatly improved survival rates for young cancer patients; however, treatment of childhood cancers can adversely impact reproductive function. Many cancer patients report a strong desire to be informed of existing options for fertility preservation and future reproduction prior to initiation of gonadotoxic cancer therapies, including surgery, chemotherapy, and radiotherapy. This article discusses, in detail, the effects of cancer treatment on fertility in men and women, and outlines both current and experimental methods of fertility preservation among cancer patients.
RESUMO
Mammalian spermatogenesis is a complex process in which spermatogonial stem cells of the testis (SSCs) develop to ultimately form spermatozoa. In the seminiferous epithelium, SSCs self-renew to maintain the pool of stem cells throughout life, or they differentiate to generate a large number of germ cells. A balance between SSC self-renewal and differentiation is therefore essential to maintain normal spermatogenesis and fertility. Stem cell homeostasis is tightly regulated by signals from the surrounding microenvironment, or SSC niche. By physically supporting the SSCs and providing them with these extrinsic molecules, the Sertoli cell is the main component of the niche. Earlier studies have demonstrated that GDNF and CYP26B1, produced by Sertoli cells, are crucial for self-renewal of the SSC pool and maintenance of the undifferentiated state. Down-regulating the production of these molecules is therefore equally important to allow germ cell differentiation. We propose that NOTCH signaling in Sertoli cells is a crucial regulator of germ cell fate by counteracting these stimulatory factors to maintain stem cell homeostasis. Dysregulation of this essential niche component can lead by itself to sterility or facilitate testicular cancer development.
RESUMO
Similar to mammals, spermatogenesis in fish is initiated by spermatogonial stem cells (SSCs) which either self-renew or gradually differentiate to produce mature sperm. SSCs are located in a particular testis microenvironment called SSC ni che, formed by Sertoli and peritubular myoid cells, the basement membrane and other cellular components/factors from the intertubular compartment that regulate SSCs maintenance and fate. Considering the great variation in testis structure/arrangemen t across fish species, the study of the niche components is crucial to understand SSCs physiology. Additionally, the germ cell transplantation technique, which has been applied to fish in the last decade, is a unique approach to elucidating important functional aspects of SSCs biology such as: (i) the capacity of SSCs to colonize the testis of recipient species (syngeneic and xenogeneic transplantation) giving rise to donor sperm; (ii) the plasticity of these cells, considering that spermatogonia and oogonia can be derived from SSCs collected from the opposite sex; and (iii) the possibility of genetically manipulating SSCs before transplantation to produce transgenic fish. However, fish SSC isolation and characterization has been lim ited so far by the lack of specific molecular markers fo r these cells. Therefore, various research groups are currently investigating specific SSCs markers and, up to date, few proteins have been identified in different spermatogonial populations from distinct fish species (e.g. Notch1, Ly75, Plzf, Oct-4, SGSA -1). Furthermore, the development of a fish SSC culture system would allow the investigation of important regulatory aspects of the SSC physiology in well-defined conditions as well as to in vitro amplify these rare cells. Overall, the study of SSC physiology, niche and transplantation in fish has opened up new scenarios for the development of aquaculture and reproductive biotechnologies such as germplasm conservation of endangered or commercially important species and the possibility of generating transgenic fish.
Assuntos
Animais , Aquicultura/tendências , Espermatogênese/fisiologia , Espermatozoides/citologia , Fisiologia , Biotecnologia/métodos , Peixes/classificaçãoRESUMO
Similar to mammals, spermatogenesis in fish is initiated by spermatogonial stem cells (SSCs) which either self-renew or gradually differentiate to produce mature sperm. SSCs are located in a particular testis microenvironment called SSC ni che, formed by Sertoli and peritubular myoid cells, the basement membrane and other cellular components/factors from the intertubular compartment that regulate SSCs maintenance and fate. Considering the great variation in testis structure/arrangemen t across fish species, the study of the niche components is crucial to understand SSCs physiology. Additionally, the germ cell transplantation technique, which has been applied to fish in the last decade, is a unique approach to elucidating important functional aspects of SSCs biology such as: (i) the capacity of SSCs to colonize the testis of recipient species (syngeneic and xenogeneic transplantation) giving rise to donor sperm; (ii) the plasticity of these cells, considering that spermatogonia and oogonia can be derived from SSCs collected from the opposite sex; and (iii) the possibility of genetically manipulating SSCs before transplantation to produce transgenic fish. However, fish SSC isolation and characterization has been lim ited so far by the lack of specific molecular markers fo r these cells. Therefore, various research groups are currently investigating specific SSCs markers and, up to date, few proteins have been identified in different spermatogonial populations from distinct fish species (e.g. Notch1, Ly75, Plzf, Oct-4, SGSA -1). Furthermore, the development of a fish SSC culture system would allow the investigation of important regulatory aspects of the SSC physiology in well-defined conditions as well as to in vitro amplify these rare cells. Overall, the study of SSC physiology, niche and transplantation in fish has opened up new scenarios for the development of aquaculture and reproductive biotechnologies such as germplasm conservation of endangered or commercially important species and the possibility of generating transgenic fish.(AU)
Assuntos
Animais , Espermatogênese/fisiologia , Espermatozoides/citologia , Fisiologia , Aquicultura/tendências , Peixes/classificação , Biotecnologia/métodosRESUMO
The sexual plasticity of fish gonads declines after the sex-differentiation period; however, the plasticity of the germ cells themselves after this stage remains poorly understood. We characterized the sexual plasticity of gonial germ cells by transplanting them into sexually undifferentiated embryonic gonads in rainbow trout (Oncorhynchus mykiss). Spermatogonia or oogonia isolated from the meiotic gonads of vasa-green fluorescent protein (Gfp) gene transgenic trout were transplanted into the peritoneal cavity of newly hatched embryos of both sexes, and the behavior of the GFPlabeled donor cells was observed. The transplanted spermatogonia and oogonia migrated towards the recipient gonadal anlagen, and were subsequently incorporated into them. We also confirmed that the donor-derived gonial germ cells resumed gametogenesis in the recipient somatic microenvironment synchronously with the endogenous germ cells. Surprisingly, the donor-derived spermatogonia started to proliferate and differentiate into oocytes in female recipients. At 2 years post-transplantation, the eggs from mature female recipients were artificially inseminated with sperm from intact male rainbow trout. Normal, live offspring with the donor-derived haplotype were obtained. In addition, oogonia-derived sperm were produced in the male recipients. These donor-derived sperm were shown to be fully functional, as live offspring carrying GFP-labeled germ cells with the donor haplotype were obtained in the first filial (F1) generation. These findings indicate that rainbow trout pre-meiotic germ cells, which are likely to be spermatogonial or oogonial stem cells, possess a high level of sexual plasticity, and that the sexual differentiation of germ cells is controlled solely by the somatic microenvironment, rather than being cell autonomous.
Assuntos
Animais , Diferenciação Sexual/fisiologia , Espermatogônias/crescimento & desenvolvimento , Oogônios/crescimento & desenvolvimento , Transplante de Células/métodos , Transplante de Células/veterinária , Oncorhynchus mykiss/crescimento & desenvolvimento , Transplante Heterólogo/efeitos adversosRESUMO
The sexual plasticity of fish gonads declines after the sex-differentiation period; however, the plasticity of the germ cells themselves after this stage remains poorly understood. We characterized the sexual plasticity of gonial germ cells by transplanting them into sexually undifferentiated embryonic gonads in rainbow trout (Oncorhynchus mykiss). Spermatogonia or oogonia isolated from the meiotic gonads of vasa-green fluorescent protein (Gfp) gene transgenic trout were transplanted into the peritoneal cavity of newly hatched embryos of both sexes, and the behavior of the GFPlabeled donor cells was observed. The transplanted spermatogonia and oogonia migrated towards the recipient gonadal anlagen, and were subsequently incorporated into them. We also confirmed that the donor-derived gonial germ cells resumed gametogenesis in the recipient somatic microenvironment synchronously with the endogenous germ cells. Surprisingly, the donor-derived spermatogonia started to proliferate and differentiate into oocytes in female recipients. At 2 years post-transplantation, the eggs from mature female recipients were artificially inseminated with sperm from intact male rainbow trout. Normal, live offspring with the donor-derived haplotype were obtained. In addition, oogonia-derived sperm were produced in the male recipients. These donor-derived sperm were shown to be fully functional, as live offspring carrying GFP-labeled germ cells with the donor haplotype were obtained in the first filial (F1) generation. These findings indicate that rainbow trout pre-meiotic germ cells, which are likely to be spermatogonial or oogonial stem cells, possess a high level of sexual plasticity, and that the sexual differentiation of germ cells is controlled solely by the somatic microenvironment, rather than being cell autonomous.(AU)