Rhox13 is required for a quantitatively normal first wave of spermatogenesis in mice

We previously described a novel germ cell-specific X-linkedreproductivehomeoboxgene (Rhox13) that is upregulated at the level of translation in response to retinoic acid (RA) in differentiating spermatogonia and preleptotene spermatocytes. We hypothesize that RHOX13 plays an essential role in male germ cell differentiation, and have tested this by creating aRhox13gene knockout (KO) mouse.Rhox13KO mice are born in expected Mendelian ratios, and adults have slightly reduced testis weights, yet a full complement of spermatogenic cell types. Young KO mice (at ~7–8 weeks of age) have a ≈50% reduction in epididymal sperm counts, but numbers increased to WT levels as the mice reach ~17 weeks of age. Histological analysis of testes from juvenile KO mice reveals a number of defects during the first wave of spermatogenesis. These include increased apoptosis, delayed appearance of round spermatids and disruption of the precise stage-specific association of germ cells within the seminiferous tubules. Breeding studies reveal that both young and aged KO males produce normal-sized litters. Taken together, our results indicate that RHOX13 is not essential for mouse fertility in a controlled laboratory setting, but that it is required for optimal development of differentiating germ cells and progression of the first wave of spermatogenesis.

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1 XENOGRAFTING OF ADULT MAMMALIAN TESTIS TISSUE

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab1 ◽

2007 ◽

Vol 19 (1) ◽

pp. 119

Author(s):

L. Arregui ◽

R. Rathi ◽

W. Zeng ◽

A. Honaramooz ◽

M. Gomendio ◽

...

Keyword(s):

Cell Differentiation ◽

Germ Cell ◽

Germ Cells ◽

Sertoli Cells ◽

Human Testis ◽

Seminiferous Tubules ◽

Donor Tissue ◽

Germ Cell Differentiation ◽

Sexually Mature ◽

Testis Tissue

Testis tissue grafting presents an option for preservation of genetic material when sperm recovery is not possible. Grafting of testis tissue from sexually immature males to immunodeficient mice results in germ cell differentiation and production of fertilization-competent sperm from different mammalian species (Honaramooz et al. 2002 Nature 418, 778–781). However, the efficiency of testis tissue xenografting from adult donors has not been critically evaluated. Spermatogenesis was arrested at meiosis in grafts from mature horses (Rathi et al. 2006 Reproduction 131, 1091–1098) and hamsters (Schlatt et al. 2002 Reproduction 124, 339–346), and no germ cell differentiation occurred in xenografts of adult human testis tissue (Schlatt et al. 2006 Hum. Reprod. 21, 384–389). The objective of this study was to investigate survival and germ cell differentiation of testis xenografts from sexually mature donors of different species. Small fragments of testis tissue from 10 donor animals of 5 species were grafted under the back skin of immunodeficient, castrated male mice (n = 37, 2–6/donor). Donors were pig (8 months old), goat (18 months old and 4 years old) (n = 2), bull (3 years old), donkey (13 months old), and rhesus monkey (3, 6, 11, and 12 years old). At the time of grafting, donor tissue contained elongated spermatids, albeit to different degrees (>75% of seminiferous tubules in testis tissue from pig, goat, bull, and 6–12-year-old monkeys, and 33 or 66% of tubules in tissue from donkey or 3-year-old monkey, respectively). Grafts were recovered <12 weeks (n = 14 mice), 12–24 weeks (n = 16 mice), and >24 weeks (n = 7 mice) after grafting and classified histologically as completely degenerated (no tubules found), degenerated tubules (only hyalinized seminiferous tubules observed), or according to the most advanced type of germ cell present. Grafts from pig, goat, bull, and 6–12-year-old monkeys contained >60% degenerated tubules or were completely degenerated at all time points analyzed. In contrast, in grafts from the 3-year-old monkey, only 18% of tubules were degenerated, 14% contained Sertoli cells only, 64% contained meiotic, and 4% haploid germ cells at 24 weeks after grafting. Similarly, donkey testis grafts recovered 12–24 weeks after grafting contained <2% degenerated tubules, 46% of tubules had Sertoli cells only, 45% contained meiotic, and 7% haploid germ cells. These results show that survival and differentiation of germ cells in testis grafts from sexually mature mammalian donors is poor. However, better graft survival and maintenance of spermatogenesis occurred in donor tissue from donkey and 3-year-old monkey that were less mature at the time of grafting. Therefore, species and age-related differences appear to exist with regard to germ cell survival and differentiation in xenografts from adult donors. This work was supported by USDA/CSREES 03-35203-13486, NIH/NCRR 5-R01-RR17359-05, the Spanish Ministry of Education, and Science (BES-2004-4112).

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Establishment of Etv5 gene knockout mice as a recipient model for spermatogonial stem cell transplantation

Biology Open ◽

10.1242/bio.056804 ◽

2020 ◽

Vol 10 (1) ◽

pp. bio056804

Author(s):

Xianyu Zhang ◽

Xin Zhao ◽

Guoling Li ◽

Mao Zhang ◽

Pingping Xing ◽

...

Keyword(s):

Stem Cell ◽

Germ Cell ◽

Cell Transplantation ◽

Germ Cells ◽

Fluorescent Protein ◽

Gene Knockout ◽

Spermatogonial Stem Cell ◽

Seminiferous Tubules ◽

Mature Adult ◽

Testicular Weight

ABSTRACTSpermatogonial stem cell (SSC) transplantation is an alternative reproductive method to achieve conservation and production of elite animals in livestock production. Creating a recipient animal without endogenous germ cells is important for effective SSC transplantation. However, natural mutants with depletion of SSCs are difficult to obtain, and drug ablation of endogenous germ cells is arduous to perform for practical use. In this study, we used mouse models to study the preparation of recipients with congenital germ cell ablation. We knocked out (KO) Ets-variant gene 5 (Etv5) in mice using the CRISPR/Cas9 system. The testicular weight of Etv5−/− mice was significantly lower than that of wild-type (WT) mice. The germ cell layer of the seminiferous tubules gradually receded with age in Etv5−/− mice. At 12 weeks of age, the tubules of Etv5−/− mice lacked almost all spermatogenic cells with a Sertoli cell-only phenotype, and sperm were completely absent in the epididymis. We subsequently transplanted allogeneic SSCs with enhanced green fluorescent protein (EGFP) into 3- (immature) or 7-week-old (mature) Etv5−/− mice. Partially restoration of germ cell layers in the seminiferous tubules and spermatogenesis was observed in all immature testes but not in mature adult testes at 2 months post-transplantation. The presence of heterologous genes Etv5 and EGFP in recipient testicular tissue and epididymal sperm by PCR indicated that sperm originated from the transplanted donor cells. Our study demonstrates that, although Etv5−/− mice could accommodate and support foreign germ cell transplantation, this process occurs in a quite low efficiency to support a full spermatogenesis of transplanted SSCs. However, using Etv5−/− mice as a recipient model for SSC transplantation is feasible, and still needs further investigation to establish an optimized transplantation process.

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Establishment of Etv5 gene knockout mice as a recipient model for spermatogonial stem cell transplantation

10.1101/2020.03.10.985408 ◽

2020 ◽

Author(s):

Xianyu Zhang ◽

Xin Zhao ◽

Guoling Li ◽

Mao Zhang ◽

Pingping Xing ◽

...

Keyword(s):

Germ Cell ◽

Cell Transplantation ◽

Germ Cells ◽

Fluorescent Protein ◽

Gene Knockout ◽

Seminiferous Tubules ◽

Post Transplantation ◽

Mature Adult ◽

Testicular Weight ◽

Low Efficiency

AbstractTransplantation of spermatogonial stem cells (SSCs) is an alternative reproductive method to achieve conservation and production of elite animals in livestock production. Creating a recipient animal without endogenous germ cells is important for effective SSC transplantation. However, natural mutants with depletion of SSCs are difficult to obtain, and drug ablation of endogenous germ cells is arduous to perform for practical use. In this study, we used mouse models to study the preparation of recipients with congenital germ cell ablation. We knocked out (KO) Ets-variant gene 5 (Etv5) in mice using the CRISPR/Cas9 system. The testicular weight of Etv5-/- mice was significantly lower than that of wild-type (WT) mice. The germ cell layer of the seminiferous tubules gradually receded with age in Etv5-/- mice. At 12 weeks of age, the tubules of Etv5-/- mice lacked germ cells (Sertoli cell-only syndrome), and sperm were completely absent in the epididymis. We subsequently transplanted allogeneic SSCs with enhanced green fluorescent protein (EGFP) into 3-(immature) or 7-week-old (mature) Etv5-/- mice. Restoration of germ cell layers in the seminiferous tubules and spermatogenesis was observed in all immature testes but not in mature adult testes at 2 months post-transplantation. The presence of heterologous genes Etv5 and EGFP in recipient testicular tissue and epididymal sperm by PCR indicated that sperm originated from the transplanted donor cells. Our study demonstrates that, although Etv5-/- mice could accommodate and support foreign germ cell transplantation, this process occurs in a quite low efficiency to support a full spermatogenesis of transplanted SSCs. However, using Etv5-/- mice as a recipient model for SSC transplantation is feasible, and still needs further investigation to establish an optimized transplantation process.

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Cell-type-specific regulation of genes involved in testicular lipid metabolism: fatty acid-binding proteins, diacylglycerol acyltransferases, and perilipin 2

Reproduction ◽

10.1530/rep-13-0199 ◽

2013 ◽

Vol 146 (5) ◽

pp. 471-480 ◽

Cited By ~ 16

Author(s):

Gerardo M Oresti ◽

Jesús García-López ◽

Marta I Aveldaño ◽

Jesús del Mazo

Keyword(s):

Fatty Acid ◽

Cell Differentiation ◽

Germ Cell ◽

Germ Cells ◽

Sertoli Cells ◽

Fatty Acid Binding Proteins ◽

Cell Type ◽

Fatty Acid Binding ◽

Germ Cell Differentiation ◽

Perilipin 2

Male germ cell differentiation entails the synthesis and remodeling of membrane polar lipids and the formation of triacylglycerols (TAGs). This requires fatty acid-binding proteins (FABPs) for intracellular fatty acid traffic, a diacylglycerol acyltransferase (DGAT) to catalyze the final step of TAG biosynthesis, and a TAG storage mode. We examined the expression of genes encoding five members of the FABP family and two DGAT proteins, as well as the lipid droplet protein perilipin 2 (PLIN2), during mouse testis development and in specific cells from seminiferous epithelium.Fabp5expression was distinctive of Sertoli cells and consequently was higher in prepubertal than in adult testis. The expression ofFabp3increased in testis during postnatal development, associated with the functional differentiation of interstitial cells, but was low in germ cells.Fabp9, together withFabp12, was prominently expressed in the latter. Their transcripts increased from spermatocytes to spermatids and, interestingly, were highest in spermatid-derived residual bodies (RB). Both Sertoli and germ cells, which produce neutral lipids and store them in lipid droplets, expressedPlin2. Yet, whileDgat1was detected in Sertoli cells,Dgat2accumulated in germ cells with a similar pattern of expression asFabp9. These results correlated with polyunsaturated fatty acid-rich TAG levels also increasing with mouse germ cell differentiation highest in RB, connecting DGAT2 with the biosynthesis of such TAGs. The age- and germ cell type-associated increases inFabp9,Dgat2, andPlin2levels are thus functionally related in the last stages of germ cell differentiation.

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Interactome analyses reveal profound proteasome structural and functional rearrangements throughout mammalian spermatogenesis

10.1101/2021.06.18.447862 ◽

2021 ◽

Author(s):

Dusan Zivkovic ◽

Angelique Sanchez Dafun ◽

Thomas Menneteau ◽

Adrien Schahl ◽

Sandrine Lise ◽

...

Keyword(s):

Mass Spectrometry ◽

Germ Cell ◽

Germ Cells ◽

Protein Assembly ◽

Homologous Chromosomes ◽

High Proteolytic Activity ◽

Complex Processes ◽

Germ Cell Differentiation ◽

Mechanism Function

During spermatogenesis, spermatogonia undergo a series of mitotic and meiotic divisions on their path to spermatozoa. To achieve this, a succession of complex processes requiring high proteolytic activity are in part orchestrated by the proteasome. The spermatoproteasome (s20S) is a proteasome subtype specific to the developing gametes, in which the gamete-specific α4s subunit replaces the α4 isoform found in the constitutive proteasome (c20S). Although the s20S is conserved across species and was shown to be crucial for germ cell development, its mechanism, function and structure remain incompletely characterized. Here, we used advanced mass spectrometry (MS) methods to map the composition of proteasome complexes and their interactomes throughout spermatogenesis. We observed that the s20S becomes highly activated as germ cells enter meiosis, mainly through association with proteasome activators PA200 and 19S. Additionally, the proteasome population shifts from predominantly c20S (98%) to predominantly s20S (>82-92%) during differentiation, presumably due to the shift from α4 to α4s expression. We confirmed that s20S, but not c20S, interacts with components of the synaptonemal complex, the multi-protein assembly that connects homologous chromosomes during meiosis. In vitro, s20S preferentially bind to 19S, and displayed higher trypsin- and chymotrypsin-like activities, both with and without PA200 activation. Moreover, using MS methods to monitor protein dynamics, we identified significant differences in domain flexibility between α4 and α4s. We propose that these differences induced by α4s incorporation result in significant changes in the way the s20S interacts with its partners, and dictate its role in germ cell differentiation.

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Minireview: Transcriptional Regulation of Gonadal Development and Differentiation

Endocrinology ◽

10.1210/en.2004-1454 ◽

2005 ◽

Vol 146 (3) ◽

pp. 1035-1042 ◽

Cited By ~ 60

Author(s):

Susan Y. Park ◽

J. Larry Jameson

Keyword(s):

Germ Cells ◽

Sertoli Cells ◽

Leydig Cells ◽

Cell Types ◽

Gonadal Development ◽

Targeted Mutagenesis ◽

Seminiferous Tubules ◽

Molecular Pathways ◽

Theca Cells ◽

Main Cell

The embryonic gonad is undifferentiated in males and females until a critical stage when the sex chromosomes dictate its development as a testis or ovary. This binary developmental process provides a unique opportunity to delineate the molecular pathways that lead to distinctly different tissues. The testis comprises three main cell types: Sertoli cells, Leydig cells, and germ cells. The Sertoli cells and germ cells reside in seminiferous tubules where spermatogenesis occurs. The Leydig cells populate the interstitial compartment and produce testosterone. The ovary also comprises three main cell types: granulosa cells, theca cells, and oocytes. The oocytes are surrounded by granulosa and theca cells in follicles that grow and differentiate during characteristic reproductive cycles. In this review, we summarize the molecular pathways that regulate the distinct differentiation of these cell types in the developing testis and ovary. In particular, we focus on the transcription factors that initiate these cascades. Although most of the early insights into the sex determination pathway were based on human mutations, targeted mutagenesis in mouse models has revealed key roles for genes not anticipated to regulate gonadal development. Defining these molecular pathways provides the foundation for understanding this critical developmental event and provides new insight into the causes of gonadal dysgenesis.

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Abnormal Meiosis Initiation in Germ Cell Caused by Aberrant Differentiation of Gonad Somatic Cell

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/8030697 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Min Chen ◽

Suren Chen ◽

Jingjing Zhou ◽

Fangfang Dong ◽

...

Keyword(s):

Cell Differentiation ◽

Germ Cell ◽

Somatic Cell ◽

Germ Cells ◽

Somatic Cells ◽

Ectopic Expression ◽

Genital Ridge ◽

Male And Female ◽

Germ Cell Differentiation ◽

Exact Function

The interaction between germ cell and somatic cell plays important roles in germ cell development. However, the exact function of gonad somatic cell in germ cell differentiation is unclear. In the present study, the function of gonad somatic cell in germ cell meiosis was examined by using mouse models with aberrant somatic cell differentiation. In Wt1R394W/R394W mice, the genital ridge is absent due to the apoptosis of coelomic epithelial cells. Interestingly, in both male and female Wt1R394W/R394W germ cells, STRA8 was detected at E12.5 and the scattered SYCP3 foci were observed at E13.5 which was consistent with control females. In Wt1-/flox; Cre-ERTM mice, Wt1 was inactivated by the injection of tamoxifen at E9.5 and the differentiation of Sertoli and granulosa cells was completely blocked. We found that most germ cells were located outside of genital ridge after Wt1 inactivation. STRA8, SYCP3, and γH2AX proteins were detected in germ cells of both male and female Wt1-/flox; Cre-ERTM gonads, whereas no thread-like SYCP3 signal was observed. Our study demonstrates that aberrant development of gonad somatic cells leads to ectopic expression of meiosis-associated genes in germ cells, but meiosis was arrested before prophase I. These results suggest that the proper differentiation of gonad somatic cells is essential for germ cell meiosis.

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Hepatocyte growth factor modulates in vitro survival and proliferation of germ cells during postnatal testis development

Journal of Endocrinology ◽

10.1677/joe.1.06528 ◽

2006 ◽

Vol 189 (1) ◽

pp. 137-146 ◽

Cited By ~ 11

Author(s):

A Catizone ◽

G Ricci ◽

J Del Bravo ◽

M Galdieri

Keyword(s):

Growth Factor ◽

Hepatocyte Growth Factor ◽

Germ Cell ◽

Germ Cells ◽

Cell Types ◽

Tyrosine Kinase Receptor ◽

Testis Development ◽

Pachytene Spermatocytes ◽

Hepatocyte Growth

The hepatocyte growth factor (HGF) is a pleiotropic cytokine that influences mitogenesis, motility and differentiation of many different cell types by its tyrosine kinase receptor c-Met. We previously demonstrated that the c-Met/HGF system is present and functionally active during postnatal testis development. We found also that spermatozoa express c-Met and that HGF has a positive effect on the maintenance of sperm motility. In the present paper, we extend our study on the germ cells at different stages of differentiation during the postnatal development of the testis. We demonstrate that c-met is present in rat spermatogonia, pachytene spermatocytes and round spermatids and that HGF significantly increases spermatogonial proliferation in 8- to 10-day-old pre-pubertal rats. At this age HGF does not affect Sertoli cells and peritubular myoid cells proliferation. In addition, we studied the effect of the factor on germ cell apoptosis and we show that HGF prevents the germ cell apoptotic process. We also studied the effect of HGF on 18- to 20-day-old and 28- to 30-day-old rat testes. At these ages also the factor significantly increases germ cell duplication and decreases the number of apoptotic cells. However, the effect on programmed cell death is higher in the 8- to 10-day-old rats and declines in the older animals. In conclusion, we report that rat germ cells (spermatogonia, pachytene spermatocytes and round spermatids) express c-met and that HGF modulates germ cell proliferating activity and apoptosis in vitro. These data indicate that the c-Met/HGF system is involved in male germ cell homeostasis and, consequently, has a role in male fertility.

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217 PROTEIN-INDUCED TRANSDIFFERENTIATION INTO MALE GERM CELL-LIKE LINEAGE FROM CHICKEN FETAL BONE MARROW STEM CELLS

Reproduction Fertility and Development ◽

10.1071/rdv24n1ab217 ◽

2012 ◽

Vol 24 (1) ◽

pp. 220

Author(s):

J. M. Yoo ◽

J. J. Park ◽

K. Gobianand ◽

J. Y. Ji ◽

J. S. Kim ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Retinoic Acid ◽

Germ Cell ◽

Germ Cells ◽

Cultured Cells ◽

Male Germ Cell ◽

Male Germ Cells ◽

Germ Cell Differentiation ◽

Transgenic Chickens

Bone marrow (BM)-derived stem cells are capable of transdifferentiation into multilineage cells like muscle, bone, cartilage, fat and nerve cells. In this study, we investigated the capability of mesenchymal stem cells (MSC) derived from BM into germ cell differentiation in the chicken. Chicken MSCs were isolated from BM of day 20 fertilized fetal chicken with Ficoll-Paque Plus. Isolated cells were cultured in advance-DMEM (ADMEM) supplemented with 10% fetal bovine serum and antibiotics. Once confluent, cells were subcultured until five passages. The cultured cells showed fibroblast-like morphology. The cells had positive expressions of Oct4, Sox2 and Nanog. Two induction methods were conducted to examine the ability of transdifferentation into male germ cells. In group 1, MSC were cultured in ADMEM containing retinoic acid and chicken testicular extracts proteins for 10 to 15 days. In group 2, MSC were permeabilized by streptolysin O and treated with chicken testicular protein extracts. In both treatment groups, MSC were cultured in ADMEM containing retinoic acid for 10 to 15 days. We found that chicken MSC had a positive expression of pluripotent proteins such as Oct4, Sox2, Nanog and a small population of chicken MSC seem to transdifferentiate into male germ cell-like cells. These cells expressed early germ cell markers and male germ-cell-specific markers (Dazl, C-kit, Stra8 and DDX4) as analysed by reverse transcription-PCR and immunohistochemistry. These results demonstrated that chicken MSC may differentiate into male germ cells and the same might be used as a potential source of cells for production of transgenic chickens. This study was carried out with the support of Agenda Program (Project No. PJ0064692011), RDA and Republic of Korea.

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286 EXPRESSION OF PLURIPOTENT STEM CELL MARKERS IN DOMESTIC CAT SPERMATOGONIAL CELLS

Reproduction Fertility and Development ◽

10.1071/rdv25n1ab286 ◽

2013 ◽

Vol 25 (1) ◽

pp. 290 ◽

Cited By ~ 4

Author(s):

R. H. Powell ◽

M. N. Biancardi ◽

J. Galiguis ◽

Q. Qin ◽

C. E. Pope ◽

...

Keyword(s):

Stem Cells ◽

Flow Cytometry ◽

Basement Membrane ◽

Germ Cell ◽

Germ Cells ◽

Spermatogonial Stem Cells ◽

Seminiferous Tubules ◽

Cell Populations ◽

Surface Markers ◽

Cell Markers

Spermatogonial stem cells (SSC), progenitor cells capable of both self-renewal and producing daughter cells that will differentiate into sperm, can be manipulated for transplantation to propagate genetically important males. This application was demonstrated in felids by the successful xeno-transplantation of ocelot mixed germ cells into the testes of domestic cats, which resulted in the production of ocelot sperm (Silva et al. 2012 J. Androl. 33, 264–276). Spermatogonial stem cells are in low numbers in the testis, but have been identified and isolated in different mammalian species using SSC surface markers; however, their expression varies among species. Until recently, little was known about the expression of SSC surface markers in feline species. We previously demonstrated that many mixed germ cells collected from adult cat testes express the germ cell markers GFRα1, GPR125, and C-Kit, and a smaller population of cells expresses the pluripotent SSC-specific markers SSEA-1 and SSEA-4 (Powell et al. 2011 Reprod. Fertil. Dev. 24, 221–222). In the present study, our goal was to identify germ cell and SSC-specific markers in SSC from cat testes. Immunohistochemical (IHC) localization of germ cell markers GFRα1, GPR125, and C-Kit and pluripotent SSC-specific markers SSEA-1, SSEA-4, TRA-1-60, TRA-1-81, and Oct-4 was detected in testis tissue from both sexually mature and prepubertal males. Testes were fixed with modified Davidson’s fixative for 24 h before processing, embedding, and sectioning. The EXPOSE Mouse and Rabbit Specific HRP/DAB detection IHC kit (Abcam®, Cambridge, MA, USA) was used for antibody detection. Staining for SSEA-1, SSEA-4, TRA-1-60, TRA-1-81, and Oct-4 markers was expressed specifically at the basement membrane of the seminiferous tubules in both adult and prepubertal testes. The GFRα1 and GPR125 markers were detected at the basement membrane of the seminiferous tubules and across the seminiferous tubule section. However, C-Kit was not detected in any cell. Using flow cytometry from a pool of cells from seven adult testes, we detected 45% GFRα1, 50% GPR125, 59% C-Kit, 18% TRA-1-60, 16% TRA-1-81 positive cells, and a very small portion of SSEA-1 (7%) and SSEA-4 (3%) positive cells. Dual staining of germ cells pooled from 3 testes revealed 3 distinct cell populations that were positive for GFRα1 only (23%), positive for both GFRα1 and SSEA-4 (6%), and positive for SSEA-4 only (1%). Our IHC staining of cat testes indicated that cells along the basement membrane of seminiferous tubules were positive for SSC-specific markers, and flow cytometry analysis revealed that there were different cell populations expressing both germ cell and SSC-specific markers. Flow cytometry results show overlapping germ cell populations expressing SSEA-4 and GFRα1, and IHC results reveal that SSEA-4 positive cells are spermatogonia, whereas GFRα1 positive cells include other stages of germ cells, indicating that the small population of cells positive only for SSEA-4 is undifferentiated cat SSC.

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