![]() Am J Med Genet 87(4):349–353Ĭox JJ et al (2011) A SOX9 duplication and familial 46, XX developmental testicular disorder. Huang B et al (1999) Autosomal XX sex reversal caused by duplication of SOX9. Wagner T et al (1994) Autosomal sex reversal and campomelic dysplasia are caused by mutations in and around the SRY-related gene SOX9. Endocr Rev 24(4):466–487įoster JW et al (1994) Campomelic dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene. Harley VR, Clarkson MJ, Argentaro A (2003) The molecular action and regulation of the testis-determining factors, SRY (sex-determining region on the Y chromosome) and SOX9. Youngren KK et al (2005) The Ter mutation in the dead end gene causes germ cell loss and testicular germ cell tumours. Sakurai T et al (1995) The ter mutation first causes primordial germ cell deficiency in ter/ter mouse embryos at 8 days of gestation. Yamaji M et al (2008) Critical function of Prdm14 for the establishment of the germ cell lineage in mice. Kurimoto K et al (2008) Specification of the germ cell lineage in mice: a process orchestrated by the PR-domain proteins, Blimp1 and Prdm14. Ohinata Y et al (2005) Blimp1 is a critical determinant of the germ cell lineage in mice. Gu Y et al (2009) Steel factor controls primordial germ cell survival and motility from the time of their specification in the allantois, and provides a continuous niche throughout their migration. Matsui Y, Zsebo KM, Hogan BL (1990) Embryonic expression of a haematopoietic growth factor encoded by the Sl locus and the ligand for c-kit. Manova K et al (1990) Gonadal expression of c-kit encoded at the W locus of the mouse. Richardson BE, Lehmann R (2010) Mechanisms guiding primordial germ cell migration: strategies from different organisms. Tremblay KD, Dunn NR, Robertson EJ (2001) Mouse embryos lacking Smad1 signals display defects in extra-embryonic tissues and germ cell formation. Mol Endocrinol 14(7):1053–1063Ĭhang H, Matzuk MM (2001) Smad5 is required for mouse primordial germ cell development. Ying Y et al (2000) Requirement of Bmp8b for the generation of primordial germ cells in the mouse. Lawson KA et al (1999) Bmp4 is required for the generation of primordial germ cells in the mouse embryo. Key wordsĮdson MA, Nagaraja AK, Matzuk MM (2009) The mammalian ovary from genesis to revelation. In this chapter, we give a brief account of major events during the development of male germ cells and focus on the functions of several crucial genes that have been studied in mutant mouse models and are potential causes of human male infertility. Although intracytoplasmic sperm injection (ICSI) can be used to bypass many fertilization obstacles to achieve fertilization with only a few extracted sperm, the widespread use of ICSI without proper knowledge for genetic testing and counseling could still potentially propagate pleiotropic gene mutations associated with male infertility and other genetic diseases (Alukal and Lamb, Urol Clin North Am 35(2):277–288, 2008). Other efforts to categorize genes involved in male fertility in mammals have suggested a total of 1,188 genes (Hermo et al., Microsc Res Tech 73(4):241–494, 2010). Fortunately, after more than two decades of phenotypic studies using knockout mice and identifying genes disrupted in spontaneous mutant mice, we have unveiled new and unexpected aspects of crucial gene functions for fertility. “Idiopathic” is a widely used adjective that is used to reflect our lack of understanding of the genetics of male fertility. Among human male infertility cases, approximately 22 % were classified as “idiopathic,” a term used to describe diseases of unknown causes, with idiopathic oligozoospermia being the most common semen abnormality (11.2 %) (Comhaire et al., Int J Androl (Suppl 7):1–53, 1987). If comparative numbers of male fertility genes are needed in mammals, extra risks of male fertility problems are associated with disruptive mutations in those genes. Apparently, extra genes and additional regulatory mechanisms are required to achieve all these unique features, and an estimated 11 % of genes are involved in fertility in Drosophila (Hackstein et al., Trends Genet 16(12):565–572, 2000). To fulfill their destiny, male germ cells undergo meiosis and extensive morphogenesis that transforms the round-shaped cells into freely motile sperm propelled by a beating flagellum to seek out their missing half. The germ cells are not programmed to perform “vital” functions but to perpetuate the species through the transfer of genetic materials to the next generation. Early in embryogenesis, cells that are destined to become germ cells take on a different destiny from other cells in the embryo.
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