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Genital Ridge (genital + ridge)
Selected AbstractsHuman and pig SRY 5, flanking sequences can direct reporter transgene expression to the genital ridge and to migrating neural crest cellsDEVELOPMENTAL DYNAMICS, Issue 3 2006Alexandre Boyer Abstract Mechanisms for sex determination vary greatly between animal groups, and include chromosome dosage and haploid,diploid mechanisms as seen in insects, temperature and environmental cues as seen in fish and reptiles, and gene-based mechanisms as seen in birds and mammals. In eutherian mammals, sex determination is genetic, and SRY is the Y chromosome located gene representing the dominant testes determining factor. How SRY took over this function from ancestral mechanisms is not known, nor is it known what those ancestral mechanisms were. What is known is that SRY is haploid and thus poorly protected from mutations, and consequently is poorly conserved between mammalian species. To functionally compare SRY promoter sequences, we have generated transgenic mice with fluorescent reporter genes under the control of various lengths of human and pig SRY 5, flanking sequences. Human SRY 5, flanking sequences (5 Kb) supported reporter transgene expression within the genital ridge of male embryos at the time of sex determination and also supported expression within migrating truncal neural crest cells of both male and female embryos. The 4.6 Kb of pig SRY 5, flanking sequences supported reporter transgene expression within the male genital ridge but not within the neural crest; however, 2.6 Kb and 1.6 Kb of pig SRY 5, flanking sequences retained male genital ridge expression and now supported extensive expression within cells of the neural crest in embryos of both sexes. When 2 Kb of mouse SRY 5, flanking sequences (,3 to ,1 Kb) were placed in front of the 1.6 Kb of pig SRY 5, flanking sequences and this transgene was introduced into mice, reporter transgene expression within the male genital ridge was retained but neural crest expression was lost. These observations suggest that SRY 5, flanking sequences from at least two mammalian species contain elements that can support transgene expression within cells of the migrating neural crest and that additional SRY 5, flanking sequences can extinguish this expression. Developmental Dynamics 235:623,632, 2006. © 2006 Wiley-Liss, Inc. [source] Migration of human and mouse primordial germ cells and colonization of the developing ovary: An ultrastructural and cytochemical study ,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2006Jaime Pereda Abstract This review is an account of the origin and migratory events of primordial germ cells until their settlement in the gonad before sexual differentiation in the human as well as mice. In this context, the morphodynamic characteristics of the migration of the primordial germ cells, the macromolecular characteristics of the extracellular matrix of the migratory pathway, and the factors involved in the germ cell guidance have been analyzed and discussed in the light of recent advances in this field, by means of immunocytochemical procedures. The events prior to gonadal morphogenesis and the origin of the somatic cell content of the human gonadal primordium have been also analyzed. In particular, evidences are presented showing that cells derived from the coelomic epithelium and mesenchyme are at the origin of the somatic components of the gonadal primordium, and that a mesonephric cell contribution to the generation of somatic cell components of the genital ridge in humans should be discarded due to the morphological stability of the different nephric structures during the period preceding the sexual differentiation of the gonad. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source] Presumptive pre-sertoli cells express genes involved in cell proliferation and cell signalling during a critical window in early testis differentiationMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2007Aron T. Cory In mammals, the pre-Sertoli cell of the male genital ridge is the first cell type to display sex specific differentiation and differential gene expression. The genetic cascade driving the differentiationof pre-Sertoli cells and ultimately testis formationis beginning to be unravelled, but many questions remain. A better understanding of the transcriptome of pre-Sertoli cells immediately after sex determination is essential in order to further understand this differentiationprocess. A mouse model expressing Red Fluorescent Protein (RFP) under the control of a hybrid mouse/pig SRY promoter (HybSRYp-RFP) was used to purify cells from embryonic day 12.0 (e12.0) male genital ridges. To compare the transcriptomes of HybSRYp-RFP cell populations versus age matched whole female genital ridges, RNA was extracted and used to generate molecular probes that were hybridized onto Affymetrix Mouse Genome 430 2.0 micro-arrays. The expression of genes considered markers for pre-Sertoli cells, including Sox9, Mis, Dhh and Fgf9 were identified within the HybSRYp-RFP expressing cell population, while markers for germ cells (Oct4, SSEA-1) and endothelial cells (Ntrk3) were not identified. In contrast, markers for ovarian somatic cell expression, including Fst and Bmp2, were identified as overexpressed within the ovarian cell population. In a general fashion, genes identified as 2.5-fold over expressed in HybSRYp-RFP expressing cells coded notably for cell signalling and extra cellular proteins. The expression of Sox10, Stc2, Fgf18, Fgf13 and Wnt6 were further characterized via whole mount in situ hybridization (WISH) on male and female genital ridges between e11.5 and e14.5. Sox10, Fgf18, Fgf13 and Stc2 gene expression was detected within the male genital ridges while Wnt6 was found diffusely within both the male and female genital ridges. These data represent the earliest comprehensive microarray expression analysis of purified presumptive pre-Sertoli cells available to date. Mol. Reprod. Dev. 74: 1491,1504, 2007. © 2007 Wiley-Liss, Inc. [source] Ectopic germline cells in embryos of Xenopus laevisDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2007Kohji Ikenishi Whether all descendants of germline founder cells inheriting the germ plasm can migrate correctly to the genital ridges and differentiate into primordial germ cells (PGCs) at tadpole stage has not been elucidated in Xenopus. We investigated precisely the location of descendant cells, presumptive primordial germ cells (pPGCs) and PGCs, in embryos at stages 23,48 by whole-mount in situ hybridization with the antisense probe for Xpat RNA specific to pPGCs and whole-mount immunostaining with the 2L-13 antibody specific to Xenopus Vasa protein in PGCs. Small numbers of pPGCs and PGCs, which were positively stained with the probe and the antibody, respectively, were observed in ectopic locations in a significant number of embryos at those stages. A few of the ectopic PGCs in tadpoles at stages 44,47 were positive in TdT-mediated dUTP digoxigenin nick end labeling (TUNEL) staining. By contrast, pPGCs in the embryos until stage 40, irrespective of their location and PGCs in the genital ridges of the tadpoles at stages 43,48 were negative in TUNEL staining. Therefore, it is evident that a portion of the descendants of germline founder cells cannot migrate correctly to the genital ridges, and that a few ectopic PGCs are eliminated by apoptosis or necrosis at tadpole stages. [source] The delicate balance between male and female sex determining pathways: potential for disruption of early steps in sexual developmentINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2010P. Koopman Summary Testes and ovaries develop from the same primordial structures, the genital ridges, in the mammalian foetus. Male development depends critically on the correct functioning of the Y-linked testis-determining gene, Sry. However, Sry is highly vulnerable to mutation, and so does not provide a very robust sex-determining mechanism. Both in testes and in ovaries, proper gonadal development involves co-ordinated regulation of the bipotential fates of a number of different cell lineages, and is dependent on intercellular signalling mechanisms. If either the testicular or ovarian pathway stalls in the early stages, mechanisms operate to engage the alternative pathway. For these reasons, the early steps in mammalian sexual development are vulnerable to genetic and environmental perturbation, and represent possible points of action of endocrine disrupting compounds. [source] Presumptive pre-sertoli cells express genes involved in cell proliferation and cell signalling during a critical window in early testis differentiationMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2007Aron T. Cory In mammals, the pre-Sertoli cell of the male genital ridge is the first cell type to display sex specific differentiation and differential gene expression. The genetic cascade driving the differentiationof pre-Sertoli cells and ultimately testis formationis beginning to be unravelled, but many questions remain. A better understanding of the transcriptome of pre-Sertoli cells immediately after sex determination is essential in order to further understand this differentiationprocess. A mouse model expressing Red Fluorescent Protein (RFP) under the control of a hybrid mouse/pig SRY promoter (HybSRYp-RFP) was used to purify cells from embryonic day 12.0 (e12.0) male genital ridges. To compare the transcriptomes of HybSRYp-RFP cell populations versus age matched whole female genital ridges, RNA was extracted and used to generate molecular probes that were hybridized onto Affymetrix Mouse Genome 430 2.0 micro-arrays. The expression of genes considered markers for pre-Sertoli cells, including Sox9, Mis, Dhh and Fgf9 were identified within the HybSRYp-RFP expressing cell population, while markers for germ cells (Oct4, SSEA-1) and endothelial cells (Ntrk3) were not identified. In contrast, markers for ovarian somatic cell expression, including Fst and Bmp2, were identified as overexpressed within the ovarian cell population. In a general fashion, genes identified as 2.5-fold over expressed in HybSRYp-RFP expressing cells coded notably for cell signalling and extra cellular proteins. The expression of Sox10, Stc2, Fgf18, Fgf13 and Wnt6 were further characterized via whole mount in situ hybridization (WISH) on male and female genital ridges between e11.5 and e14.5. Sox10, Fgf18, Fgf13 and Stc2 gene expression was detected within the male genital ridges while Wnt6 was found diffusely within both the male and female genital ridges. These data represent the earliest comprehensive microarray expression analysis of purified presumptive pre-Sertoli cells available to date. Mol. Reprod. Dev. 74: 1491,1504, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||