The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Blanche Capel - One of the best experts on this subject based on the ideXlab platform.

  • Loss of Cbx2 in XY cells leads to upregulation of the ovary pathway.
    2019
    Co-Authors: Alexandra S. Garcia-moreno, Blanche Capel, Yi-tzu Lin, Christopher R. Futtner, Isabella M. Salamone, Danielle M. Maatouk
    Abstract:

    E13.5 (A-D) and E12.5 (E-G”) are stained with the pregranulosa cell marker FOXL2 (green), Sertoli cell marker SOX9 (red), and germ cell and vasculature marker PECAM (blue). WT XX gonads have FOXL2-expressing pregranulosa cells (A), whereas WT XY gonads have SOX9-expressing Sertoli cells (red), which are organized around germ cells forming Testis Cords (B). (C&D) Loss of Cbx2 in E13.5 XY gonads leads to reduction of SOX9+ Sertoli cells (red) and gain of FOXL2+ pregranulosa cells (green). Some individual cells express both markers (yellow, arrowheads in D). Testis Cords are lost and the morphology resembles WT XX gonads (A). XY gonads of single heterozygotes show no evidence of FOXL2 expression (E, F). The anterior (left, eg. E’) and posterior (right, eg. E”) poles of each gonad are enlarged in the bottom row. Gonads of Cbx2;Fgf9 double heterozygous mice (G) have FOXL2+ pregranulosa cells at the gonadal poles (G’ and G”). Some individual cells express both markers (yellow, arrowhead). A magnified view in single channels of the cell indicated by the arrowhead are in the upper-right corner (G”). Scale bars, 50μm.

  • Fetal macrophages mediate vascularization and cord formation during Testis organogenesis
    The FASEB Journal, 2015
    Co-Authors: Blanche Capel, Tony Defalco, Jonah Cool
    Abstract:

    During Testis organogenesis, Sertoli cell progenitors undergo an unusual process of de novo organization to form Testis Cords. Sertoli cells are a driving force in the formation of these epithelial...

  • Yolk-sac–derived macrophages regulate fetal Testis vascularization and morphogenesis
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Tony Defalco, Indrashis Bhattacharya, Alyna V. Williams, Dustin M. Sams, Blanche Capel
    Abstract:

    Organogenesis of the Testis is initiated when expression of Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. The cells in the early bipotential gonad undergo de novo organization to form Testis Cords that enclose germ cells inside tubules lined by epithelial Sertoli cells. Although Sertoli cells are a driving force in the de novo formation of Testis Cords, recent studies in mouse showed that reorganization of the vasculature and of interstitial cells also play critical roles in Testis cord morphogenesis. However, the mechanism driving reorganization of the vasculature during fetal organogenesis remained unclear. Here we demonstrate that fetal macrophages are associated with nascent gonadal and mesonephric vasculature during the initial phases of Testis morphogenesis. Macrophages mediate vascular reorganization and prune errant germ cells and somatic cells after Testis architecture is established. We show that gonadal macrophages are derived from primitive yolk-sac hematopoietic progenitors and exhibit hallmarks of M2 activation status, suggestive of angiogenic and tissue remodeling functions. Depletion of macrophages resulted in impaired vascular reorganization and abnormal cord formation. These findings reveal a previously unappreciated role for macrophages in Testis morphogenesis and suggest that macrophages are an intermediary between neovascularization and organ architecture during fetal organogenesis.

  • ARTICLE NO. DB989068 Sertoli Cells of the Mouse Testis Originate
    2013
    Co-Authors: From The Coelomic Epithelium, Jeannie Karl, Blanche Capel
    Abstract:

    During mouse development, the gonad begins to form shortly before 10.5 days postcoitum (dpc) on the ventromedial side of the mesonephros. The XY gonad consists of germ cells and somatic cells. The origin of the germ cells is clearly established; however, the origin of the somatic cells, especially the epithelial supporting cell lineages, called Sertoli cells, is still unclear. Sertoli cells are the first somatic cell type to differentiate in the Testis and are thought to express Sry, the male sex-determining gene, and to play a crucial role in directing Testis development. Previous data have suggested that the somatic cells of the gonad may arise from the mesonephric tubules, the mesonephric mesenchyme, or the coelomic epithelium. Immunohistochemical staining of the gonad at 11.5 dpc showed that the basement membrane barrier under the coelomic epithelium is discontinuous, suggesting that cells in the coelomic epithelium at this stage might move inward. To test this possibility directly, cells of the coelomic epithelium were labeled using the fluorescent lipophilic dye, DiI. We show that when labeled at tail somite 15–17 stages, corresponding to 11.2–11.4 dpc, the coelomic epithelial cells of both sexes migrated into the gonad. In XY gonads, the migrating coelomic epithelial cells became Sertoli cells, as well as interstitial cells. This ability of the coelomic epithelium to give rise to Sertoli cells was developmentally regulated. When labeled at tail somite 18–20 stages, corresponding to 11.5–11.7 dpc, the coelomic epithelial cells no longer became Sertoli cells. Instead, cells that migrated into the gonad stayed outside Testis Cords, in the interstitium. Migration gradually decreased and ceased by tail somite 30 stage, corresponding to 12.5 dpc, after Testis Cords had formed and the basemen

  • Germ Cells Are Not Required to Establish the Female Pathway in Mouse Fetal Gonads
    PloS one, 2012
    Co-Authors: Danielle M. Maatouk, Lindsey Mork, Ashley Hinson, Akio Kobayashi, Andrew P. Mcmahon, Blanche Capel
    Abstract:

    The fetal gonad is composed of a mixture of somatic cell lineages and germ cells. The fate of the gonad, male or female, is determined by a population of somatic cells that differentiate into Sertoli or granulosa cells and direct Testis or ovary development. It is well established that germ cells are not required for the establishment or maintenance of Sertoli cells or Testis Cords in the male gonad. However, in the agametic ovary, follicles do not form suggesting that germ cells may influence granulosa cell development. Prior investigations of ovaries in which pre-meiotic germ cells were ablated during fetal life reported no histological changes during stages prior to birth. However, whether granulosa cells underwent normal molecular differentiation was not investigated. In cases where germ cell loss occurred secondary to other mutations, transdifferentiation of granulosa cells towards a Sertoli cell fate was observed, raising questions about whether germ cells play an active role in establishing or maintaining the fate of granulosa cells. We developed a group of molecular markers associated with ovarian development, and show here that the loss of pre-meiotic germ cells does not disrupt the somatic ovarian differentiation program during fetal life, or cause transdifferentiation as defined by expression of Sertoli markers. Since we do not find defects in the ovarian somatic program, the subsequent failure to form follicles at perinatal stages is likely attributable to the absence of germ cells rather than to defects in the somatic cells.

Humphrey H C Yao - One of the best experts on this subject based on the ideXlab platform.

  • Mapping lineage progression of somatic progenitor cells in the mouse fetal Testis.
    Development (Cambridge England), 2016
    Co-Authors: Chang Liu, Karina F. Rodriguez, Humphrey H C Yao
    Abstract:

    Testis morphogenesis is a highly orchestrated process involving lineage determination of male germ cells and somatic cell types. Although the origin and differentiation of germ cells are known, the developmental course specific for each somatic cell lineage has not been clearly defined. Here, we construct a comprehensive map of somatic cell lineage progression in the mouse Testis. Both supporting and interstitial cell lineages arise from WT1+ somatic progenitor pools in the gonadal primordium. A subpopulation of WT1+ progenitor cells acquire SOX9 expression and become Sertoli cells that form Testis Cords, whereas the remaining WT1+ cells contribute to progenitor cells in the Testis interstitium. Interstitial progenitor cells diversify through the acquisition of HES1, an indication of Notch activation, at the onset of sex determination. HES1+ interstitial progenitors, through the action of Sertoli cell-derived Hedgehog signals, become positive for GLI1. The GLI1+ interstitial cells eventually develop into two cell lineages: steroid-producing fetal Leydig cells and non-steroidogenic cells. The fetal Leydig cell population is restricted by Notch2 signaling from the neighboring somatic cells. The non-steroidogenic progenitor cells retain their undifferentiated state during fetal stage and become adult Leydig cells in post-pubertal Testis. These results provide the first lineage progression map that illustrates the sequential establishment of somatic cell populations during Testis morphogenesis.

  • Loss of Smad4 in Sertoli and Leydig Cells Leads to Testicular Dysgenesis and Hemorrhagic Tumor Formation in Mice
    Biology of reproduction, 2014
    Co-Authors: Denise R Archambeault, Humphrey H C Yao
    Abstract:

    As the central component of canonical TGFbeta superfamily signaling, SMAD4 is a critical regulator of organ development, patterning, tumorigenesis, and many other biological processes. Because numerous TGFbeta superfamily ligands are expressed in developing testes, there may exist specific requirements for SMAD4 in individual testicular cell types. Previously, we reported that expansion of the fetal Testis Cords requires expression of SMAD4 by the Sertoli cell lineage. To further uncover the role of Smad4 in murine testes, we produced conditional knockout mice lacking Smad4 in either Leydig cells or in both Sertoli and Leydig cells simultaneously. Loss of Smad4 concomitantly in Sertoli and Leydig cells led to underdevelopment of the Testis Cords during fetal life and mild testicular dysgenesis in young adulthood (decreased Testis size, partially dysgenic seminiferous tubules, and low sperm production). When the Sertoli/Leydig cell Smad4 conditional knockout mice aged (56- to 62-wk old), the Testis phenotypes became exacerbated with the appearance of hemorrhagic tumors, Leydig cell adenomas, and a complete loss of spermatogenesis. In contrast, loss of Smad4 in Leydig cells alone did not appreciably alter fetal and adult Testis development. Our findings support a cell type-specific requirement of Smad4 in Testis development and suppression of testicular tumors.

  • Title: Loss of Smad4 in Sertoli and Leydig cells leads to testicular dysgenesis and hemorrhagic tumor formation in mice 1 Short title: SMAD4 in spermatogenesis and Testis tumorigenesis
    2014
    Co-Authors: Denise R Archambeault, Humphrey H C Yao
    Abstract:

    As the central component of canonical TGFbeta superfamily signaling, SMAD4 is a critical regulator of organ development, patterning, tumorigenesis, and many other biological processes. Since numerous TGFbeta superfamily ligands are expressed in developing testes, there may exist specific requirements for SMAD4 in individual testicular cell types. Previously, we reported that expansion of the fetal Testis Cords requires expression of SMAD4 by the Sertoli cell lineage. To further uncover the role of Smad4 in murine testes, we produced conditional knockout mice lacking Smad4 in either Leydig cells or in both Sertoli and Leydig cells simultaneously. Loss of Smad4 concomitantly in Sertoli and Leydig cells led to underdevelopment of the Testis Cords during fetal life and mild testicular dysgenesis in young adulthood (decreased Testis size, partially dysgenic seminiferous tubules, and low sperm production). When the Sertoli/Leydig cell Smad4 conditional knockout mice aged (56-62 wk old), the Testis phenotypes became exacerbated with the appearance of hemorrhagic tumors, Leydig cell adenomas, and a complete loss of spermatogenesis. In contrast, loss of Smad4 in Leydig cells alone did not appreciably alter fetal and adult Testis development. Our findings support a cell type-specific requirement of Smad4 in Testis development and suppression of testicular tumors.

  • Testicular somatic cells, not gonocytes, are the major source of functional activin A during Testis morphogenesis.
    Endocrinology, 2011
    Co-Authors: Denise R Archambeault, Jessica Tomaszewski, Andrew J. Childs, Richard A. Anderson, Humphrey H C Yao
    Abstract:

    Proper development of the seminiferous tubules (or Testis Cords in embryos) is critical for male fertility. Sertoli cells, somatic components of the seminiferous tubules, serve as nurse cells to the male germline, and thus their numbers decide the quantity of sperm output in adulthood. We previously identified activin A, the protein product of the activin βA (Inhba) gene, as a key regulator of murine Sertoli cell proliferation and Testis cord expansion during embryogenesis. Although our genetic studies implicated fetal Leydig cells as the primary producers of testicular activin A, gonocytes are another potential source. To investigate the relative contribution of gonocyte-derived activin A to Testis morphogenesis, we compared Testis development in the Inhba global knockout mouse, which lacks activin A production in all cells (including the gonocytes), and a steroidogenic factor 1 (Sf1)-specific conditional knockout model in which activin A expression in testicular somatic cells is disrupted but gonocyte e...

  • Reply to Sun et al.: Roles of adult Leydig cell-derived activin A remain to be determined
    Proceedings of the National Academy of Sciences, 2010
    Co-Authors: Denise R Archambeault, Humphrey H C Yao
    Abstract:

    The complicated and sometimes confusing relationship between activin A and germ cell development has been studied for many decades both in vitro and in vivo. With regard to our publication in PNAS (1), the letter by Sun et al. (2) raises an excellent point in stressing the possible effects of adult Leydig cell-derived activin A on developing germ cells. In their letter, Sun et al. (2) provide a judicious reminder of an issue that we discussed many times during collection of this data—namely, what role does loss of adult Leydig cell-derived activin A play in the testicular phenotype that we observed in adult Inhba conditional knockout (cKO) mice? As presented in our PNAS article (1), conditional removal of Inhba within Amhr2-positive Leydig cells led to obvious fetal defects, including reduced coiling of Testis Cords and enlargement of Testis cord diameter. By the time that the Inhba cKO mice were young adults, their testes exhibited enlarged seminiferous tubule diameter and various spermatogenic abnormalities. As Sun et al. (2) pointed out, the Amhr2-cre used to excise Inhba in fetal Leydig cells is also expressed in adult Leydig cells (3). Thus, the Inhba cKO mouse model that we developed is not able to clarify whether the adult testicular dysgenesis is caused solely by fetal defects or whether it additionally reflects the disruption of postnatal activin A production by adult Leydig cells.

Peter Koopman - One of the best experts on this subject based on the ideXlab platform.

  • SOX4 regulates gonad morphogenesis and promotes male germ cell differentiation in mice
    Developmental biology, 2017
    Co-Authors: Liang Zhao, Michel G. Arsenault, Enya Longmuss, Tevin Chui-ying Chau, Sunny Hartwig, Peter Koopman
    Abstract:

    The group C SOX transcription factors SOX4, -11 and -12 play important and mutually overlapping roles in development of a number of organs. Here, we examined the role of SoxC genes during gonadal development in mice. All three genes were expressed in developing gonads of both sexes, predominantly in somatic cells, with Sox4 being most strongly expressed. Sox4 deficiency resulted in elongation of both ovaries and testes, and an increased number of Testis Cords. While female germ cells entered meiosis normally, male germ cells showed reduced levels of differentiation markers Nanos2 and Dnmt3l and increased levels of pluripotency genes Cripto and Nanog, suggesting that SOX4 may normally act to restrict the pluripotency period of male germ cells and ensure their proper differentiation. Finally, our data reveal that SOX4 (and, to a lesser extent, SOX11 and -12) repressed transcription of the sex-determining gene Sox9 via an upstream Testis-specific enhancer core (TESCO) element in fetal gonads, raising the possibility that SOXC proteins may function as transcriptional repressors in a context-dependent manner.

  • Development of the Testis
    Reference Module in Biomedical Sciences, 2017
    Co-Authors: Emanuele Pelosi, Peter Koopman
    Abstract:

    Testes in male mammals develop during fetal life shortly after sex determination. The action of the Y-chromosomal gene Sry sets in train a network of gene activity that induces formation of testes from primordial tissues known as gonadal ridges; this gene activity also suppresses formation of ovaries, which form from the gonadal ridges in females, in the absence of Sry. Specifically, genes such as Sox9 acting downstream from Sry induce the differentiation of Sertoli cells, which play an instructive role in the differentiation of other testicular cell types. Testis Cords form, encasing the germ cells, and steroidogenic Leydig cells develop in the interstitium between the Cords, allowing the Testis to acquire its basic functions of generating sperm and producing male hormones. Here, we describe in detail the complex molecular and cellular events that underlie Testis development, and how misregulation of these events can give rise to disorders of sex development.

  • Female-to-male sex reversal in mice caused by transgenic overexpression of Dmrt1
    2016
    Co-Authors: Liang Zhao, Terje Svingen, Peter Koopman
    Abstract:

    Genes related to Dmrt1, which encodes a DNA-binding DM domain transcription factor, act as triggers for primary sex determination in a broad range of metazoan species. However, this role is fulfilled in mammalsbySry, anewlyevolvedgeneon theYchromosome, such that Dmrt1 has become dispensable for primary sex determination and instead maintains Sertoli cell phenotype in postnatal testes. Here, we report that enforced expression of Dmrt1 in XX mouse fetal gonads using a Wt1-BAC transgene system is sufficient to drive testicular differentiation and male secondary sex development. XX transgenic fetal gonads showed typical testicular size and vasculature. Keyovarian markers, including Wnt4 and Foxl2, were repressed. Sertoli cells expressing the hallmark Testis-determining gene Sox9 were formed, although they did not assemble into normal Testis Cords. Other bipotential lineages differentiated into testicular cell types, including steroidogenic fetal Leydig cells and non-meiotic germ cells. As a consequence, male internal and external reproductive organs developed postnatally, with an absence of female reproductive tissues. These results reveal that Dmrt1 has retained its ability to act as the primary Testis-determining trigger in mammals, even though this function isno longernormally required. Thus,Dmrt1providesacommon thread in the evolution of sex determinationmechanisms inmetazoans

  • Primary cilia function regulates the length of the embryonic trunk axis and urogenital field in mice
    Developmental biology, 2014
    Co-Authors: Elanor N. Wainwright, Terje Svingen, Carol Wicking, Peter Koopman
    Abstract:

    The issues of whether and how some organs coordinate their size and shape with the blueprint of the embryo axis, while others appear to regulate their morphogenesis autonomously, remain poorly understood. Mutations in Ift144, encoding a component of the trafficking machinery of primary cilia assembly, result in a range of embryo patterning defects, affecting the limbs, skeleton and neural system. Here, we show that embryos of the mouse mutant Ift144(twt) develop gonads that are larger than wildtype. Investigation of the early patterning of the urogenital ridge revealed that the anterior posterior domain of the gonad/mesonephros was extended at 10.5 dpc, with no change in the length of the metanephros. In XY embryos, this extension resulted in an increase in Testis cord number. Moreover, we observed a concomitant extension of the trunk axis in both sexes, with no change in the length of the tail domain or somite number. Our findings support a model in which: (1) primary cilia regulate embryonic trunk elongation; (2) the length of the trunk axis determines the size of the urogenital ridges; and (3) the gonad domain is partitioned into a number of Testis Cords that depends on the available space, rather than being divided a predetermined number of times to generate a specific number of Cords. (C) 2014 Elsevier Inc. All rights reserved.

  • Profiles of Gonadal Gene Expression in the Developing Bovine Embryo
    Sexual development : genetics molecular biology evolution endocrinology embryology and pathology of sex determination and differentiation, 2009
    Co-Authors: Diana G. F. Ross, Josephine Bowles, Michelle Hope, Sigrid A. Lehnert, Peter Koopman
    Abstract:

    Our current understanding of the molecular basis of sex determination and gonadal development in humans is mostly an extrapolation of knowledge gained from studies in the mouse. However, the timing of gene expression in the mouse is unusual among mammals, and it is therefore important that data from other models are also available to help elucidate this pivotal process in human development. Here we describe the sequence of molecular and morphological events marking Testis differentiation in bovine embryos. The genital ridges first appeared at CRL 12 (day 32). SRY expression began at CRL 18 (day 37) and peaked at CRL 20 (day 39), leading to a cascade of regulatory, signaling, and steroidogenic gene expression at later stages, detected by quantitative real-time RT-PCR and immunohistochemistry. Testis Cords were distinguishable at CRL 27 (day 42). We conclude that the timing of gene expression observed in developing human embryos is much more similar to bovine development than it is to the mouse. Therefore, Bos taurus may represent a useful model in which to study gene expression during sex determination, relevant to human development.

Gerd Scherer - One of the best experts on this subject based on the ideXlab platform.

  • Sox9 and Sox8 Are Required for Basal Lamina Integrity of Testis Cords and for Suppression of FOXL2 During Embryonic Testis Development in Mice
    Biology of reproduction, 2012
    Co-Authors: Ina Georg, Francisco J Barrionuevo, Thorsten Wiech, Gerd Scherer
    Abstract:

    The sex-determining gene Sry and its target gene Sox9 initiate the early steps of Testis development in mammals. Of the related Sox genes Sox8, Sox9, and Sox10, all expressed during Sertoli cell differentiation, only inactivation of Sox9 before the sex determination stage at Embryonic Day 11.5 (E11.5) causes XY sex reversal, while Sox9 inactivation after this stage has no effect on Testis cord differentiation. We have previously shown that both Sox9 and Sox8 are essential for maintaining testicular function in post-E14.0 Sertoli cells. To gain insight into the molecular and cellular processes underlying the abnormal development of Sox9 and Sox8 mutant testes, we performed a detailed developmental study of embryonic and neonatal stages. We observe a progressive disruption of the basal lamina surrounding the Testis Cords that starts at E17.5 and already at E15.5 reduced expression levels of collagen IV, collagen IXa3 and testatin, structural components of the basal lamina, and the extracellular matrix transcriptional regulator Scleraxis. Lineage tracing reveals that mutant Sertoli cells delaminate from Testis Cords and are present as isolated cells between remaining Cords. Also, Sox10 expression is strongly reduced in the absence of Sox9 and/or Sox8. Finally, we document increasing expression of the ovarian marker FOXL2 in mutant Cords starting at E15.5, indicating progressive transdifferentiation of mutant Sertoli cells. This study shows that Sox9 and Sox8 maintain integrity of the basal lamina to prevent Testis cord disintegration and that both factors actively suppress the ovarian program during early Testis development.

  • Testis cord differentiation after the sex determination stage is independent of Sox9 but fails in the combined absence of Sox9 and Sox8
    Developmental Biology, 2009
    Co-Authors: F. Barrionuevo, Michael Wegner, Ina Georg, Harry Scherthan, Charlotte Lécureuil, Florian Jean Louis Guillou, Gerd Scherer
    Abstract:

    Sox9 and Sox8 are transcription factors expressed in embryonic and postnatal Sertoli cells of the mouse Testis. Sox9 inactivation prior to the sex determination stage leads to complete XY sex reversal. In contrast, there is normal embryonic Testis development in Sox8 mutants which are initially fertile, but later develop progressive seminiferous tubule failure and infertility. To determine whether Sox9 is required for Testis development after the initial steps of sex determination, we crossed Sox9(flox) mice with an AMH-Cre transgenic line thereby completely deleting Sox9 in Sertoli cells by E14.0. Conditional Sox9 null mutants show normal embryonic Testis development and are initially fertile, but, like Sox8(-1-) mutants, become sterile from dysfunctional spermatogenesis at about 5 months. To see whether Sox8 may compensate for the absence of Sox9 during embryonic Testis differentiation, we generated a Sox9 conditional knockout on a Sox8 mutant background. In the double mutants, differentiation of Testis Cords into seminiferous Testis tubules ceases after P6 in the absence of one Sox8 allele, and after PO in the absence of both Sox8 alleles, leading to complete primary infertility. Sox9,Sox8 double nullizygous testes show upregulation of early ovary-specific markers and downregulation of Sertoli intercellular junctions at E15.5. Their very low Amh levels still cause complete regression of the Mullerian duct but with reduced penetrance. This study shows that Testis cord differentiation is independent of Sox9, and that concerted Sox9 and Sox8 function in post E14.0 Sertoli cells is essential for the maintenance of testicular function. (C) 2008 Elsevier Inc. All rights reserved.

  • Testis cord differentiation after the sex determination stage is independent of Sox9 but fails in the combined absence of Sox9 and Sox8
    Developmental biology, 2008
    Co-Authors: Francisco J Barrionuevo, Michael Wegner, Ina Georg, Harry Scherthan, Charlotte Lécureuil, Florian Guillou, Gerd Scherer
    Abstract:

    Sox9 and Sox8 are transcription factors expressed in embryonic and postnatal Sertoli cells of the mouse Testis. Sox9 inactivation prior to the sex determination stage leads to complete XY sex reversal. In contrast, there is normal embryonic Testis development in Sox8 mutants which are initially fertile, but later develop progressive seminiferous tubule failure and infertility. To determine whether Sox9 is required for Testis development after the initial steps of sex determination, we crossed Sox9(flox) mice with an AMH-Cre transgenic line thereby completely deleting Sox9 in Sertoli cells by E14.0. Conditional Sox9 null mutants show normal embryonic Testis development and are initially fertile, but, like Sox8(-/-) mutants, become sterile from dysfunctional spermatogenesis at about 5 months. To see whether Sox8 may compensate for the absence of Sox9 during embryonic Testis differentiation, we generated a Sox9 conditional knockout on a Sox8 mutant background. In the double mutants, differentiation of Testis Cords into seminiferous Testis tubules ceases after P6 in the absence of one Sox8 allele, and after P0 in the absence of both Sox8 alleles, leading to complete primary infertility. Sox9,Sox8 double nullizygous testes show upregulation of early ovary-specific markers and downregulation of Sertoli intercellular junctions at E15.5. Their very low Amh levels still cause complete regression of the Mullerian duct but with reduced penetrance. This study shows that Testis cord differentiation is independent of Sox9, and that concerted Sox9 and Sox8 function in post E14.0 Sertoli cells is essential for the maintenance of testicular function.

Andrew H Sinclair - One of the best experts on this subject based on the ideXlab platform.

  • anti mullerian hormone is required for chicken embryonic urogenital system growth but not sexual differentiation
    Biology of Reproduction, 2015
    Co-Authors: Luke S Lambeth, Katie L Ayers, Andrew D Cutting, Timothy J Doran, Andrew H Sinclair, Craig A Smith
    Abstract:

    ABSTRACT In mammals, the primary role of anti-Mullerian hormone (AMH) during development is the regression of Mullerian ducts in males. These structures otherwise develop into fallopian tubes, oviducts, and upper vagina, as in females. This highly conserved function is retained in birds and is supported by the high levels of AMH expression in developing testes. In mammals, AMH expression is controlled partly by the transcription factor, SOX9. However, in the chicken, AMH mRNA expression precedes that of SOX9 , leading to the view that AMH may lie upstream of SOX9 and play a more central role in avian testicular development. To help define the role of AMH in chicken gonad development, we suppressed AMH expression in chicken embryos using RNA interference. In males, AMH knockdown did not affect the expression of key Testis pathway genes, and Testis Cords developed normally. However, a reduction in the size of the mesonephros and gonads was observed, a phenotype that was evident in both sexes. This growth de...

  • Anti-Müllerian Hormone Is Required for Chicken Embryonic Urogenital System Growth but Not Sexual Differentiation
    Biology of reproduction, 2015
    Co-Authors: Luke S Lambeth, Katie L Ayers, Andrew D Cutting, Timothy J Doran, Andrew H Sinclair, Craig A Smith
    Abstract:

    In mammals, the primary role of anti-Mullerian hormone (AMH) during development is the regression of Mullerian ducts in males. These structures otherwise develop into fallopian tubes, oviducts, and upper vagina, as in females. This highly conserved function is retained in birds and is supported by the high levels of AMH expression in developing testes. In mammals, AMH expression is controlled partly by the transcription factor, SOX9. However, in the chicken, AMH mRNA expression precedes that of SOX9 , leading to the view that AMH may lie upstream of SOX9 and play a more central role in avian testicular development. To help define the role of AMH in chicken gonad development, we suppressed AMH expression in chicken embryos using RNA interference. In males, AMH knockdown did not affect the expression of key Testis pathway genes, and Testis Cords developed normally. However, a reduction in the size of the mesonephros and gonads was observed, a phenotype that was evident in both sexes. This growth defect occurred as a result of the reduced proliferative capacity of the cells of these tissues, and male gonads also had a significant reduction in germ cell numbers. These data suggest that although AMH does not directly contribute to testicular or ovarian differentiation, it is required in a sex-independent manner for proper cell proliferation and urogenital system growth.

  • Identification, Expression, and Regulation of Anti-Müllerian Hormone Type-II Receptor in the Embryonic Chicken Gonad
    Biology of reproduction, 2014
    Co-Authors: Andrew D Cutting, Katie L Ayers, Timothy J Doran, Andrew H Sinclair, N. Davidson, Alicia Oshlack, Mark Tizard, Craig A Smith
    Abstract:

    Anti-Mullerian hormone (AMH) signaling is required for proper development of the urogenital system in vertebrates. In male mammals, AMH is responsible for regressing the Mullerian ducts, which otherwise develop into the fallopian tubes, oviducts, and upper vagina of the female reproductive tract. This role is highly conserved across higher vertebrates. However, AMH is required for Testis development in fish species that lack Mullerian ducts, implying that AMH signaling has broader roles in other vertebrates. AMH signals through two serine/threonine kinase receptors. The primary AMH receptor, AMH receptor type-II (AMHR2), recruits the type I receptor, which transduces the signal intracellularly. To enhance our understanding of AMH signaling and the potential role of AMH in gonadal sex differentiation, we cloned chicken AMHR2 cDNA and examined its expression profile during gonadal sex differentiation. AMHR2 is expressed in the gonads and Mullerian ducts of both sexes but is more strongly expressed in males after the onset of gonadal sex differentiation. In the testes, the AMHR2 protein colocalizes with AMH, within Sertoli cells of the Testis Cords. AMHR2 protein expression is up-regulated in female embryos treated with the estrogen synthesis inhibitor fadrozole. Conversely, knockdown of the key Testis gene DMRT1 leads to disruption of AMHR2 expression in the developing seminiferous Cords of males. These results indicate that AMHR2 is develop- mentally regulated during testicular differentiation in the chicken embryo. AMH signaling may be important for gonadal differentiation in addition to Mullerian duct regression in birds. AMH, AMHR2, AMH type-II receptor, DMRT1, embryonic chicken gonad, sex determination

  • Mitotic arrest in teratoma susceptible fetal male germ cells.
    PloS one, 2011
    Co-Authors: Patrick S. Western, Jocelyn Van Den Bergen, Rachael A Ralli, Stephanie I. Wakeling, Denise C. Miles, Andrew H Sinclair
    Abstract:

    Formation of germ cell derived teratomas occurs in mice of the 129/SvJ strain, but not in C57Bl/6 inbred or CD1 outbred mice. Despite this, there have been few comparative studies aimed at determining the similarities and differences between teratoma susceptible and non-susceptible mouse strains. This study examines the entry of fetal germ cells into the male pathway and mitotic arrest in 129T2/SvJ mice. We find that although the entry of fetal germ cells into mitotic arrest is similar between 129T2/SvJ, C57Bl/6 and CD1 mice, there were significant differences in the size and germ cell content of the Testis Cords in these strains. In 129T2/SvJ mice germ cell mitotic arrest involves upregulation of p27KIP1, p15INK4B, activation of RB, the expression of male germ cell differentiation markers NANOS2, DNMT3L and MILI and repression of the pluripotency network. The germ-line markers DPPA2 and DPPA4 show reciprocal repression and upregulation, respectively, while FGFR3 is substantially enriched in the nucleus of differentiating male germ cells. Further understanding of fetal male germ cell differentiation promises to provide insight into disorders of the Testis and germ cell lineage, such as Testis tumour formation and infertility.

  • The avian Z-linked gene DMRT1 is required for male sex determination in the chicken
    Nature, 2009
    Co-Authors: Craig A Smith, Timothy J Doran, Kelly N. Roeszler, Thomas Ohnesorg, David M. Cummins, Peter G. Farlie, Andrew H Sinclair
    Abstract:

    Sex in birds is chromosomally based, as in mammals, but the sex chromosomes are different and the mechanism of avian sex determination has been a long-standing mystery. In the chicken and all other birds, the homogametic sex is male (ZZ) and the heterogametic sex is female (ZW). Two hypotheses have been proposed for the mechanism of avian sex determination. The W (female) chromosome may carry a dominant-acting ovary determinant. Alternatively, the dosage of a Z-linked gene may mediate sex determination, two doses being required for male development (ZZ). A strong candidate avian sex-determinant under the dosage hypothesis is the conserved Z-linked gene, DMRT1 (doublesex and mab-3-related transcription factor 1). Here we used RNA interference (RNAi) to knock down DMRT1 in early chicken embryos. Reduction of DMRT1 protein expression in ovo leads to feminization of the embryonic gonads in genetically male (ZZ) embryos. Affected males show partial sex reversal, characterized by feminization of the gonads. The feminized left gonad shows female-like histology, disorganized Testis Cords and a decline in the testicular marker, SOX9. The ovarian marker, aromatase, is ectopically activated. The feminized right gonad shows a more variable loss of DMRT1 and ectopic aromatase activation, suggesting differential sensitivity to DMRT1 between left and right gonads. Germ cells also show a female pattern of distribution in the feminized male gonads. These results indicate that DMRT1 is required for Testis determination in the chicken. Our data support the Z dosage hypothesis for avian sex determination.