development of mammals

During the development of mammals are the sex glands (gonads) in the first place, both the ovary and testis to develop [1]. When people from around the 4th Week, the facilities of the sex glands in the intermediate mesoderm in the vicinity of the developing kidneys available. Week 6 in some form genital epithelial strands within the developing testes and take the gametes (reproductive cells) when they walk in on the sex glands. In men control certain Y-chromosome gene, SRY, in particular the development of the male phenotype, including the transformation of the early bipotentialen sex gland in the testicles. In men invade the genital strands entirely in the evolving sex glands On.

Until Week 8 of the humane Fetalentwicklung appear Leydig cells differentiating itself in the sex glands of the man. From the mesoderm derived epithelial cells of the genital strands in the forming testes develop into the Sertoli cells, which have the function and the formation of sperm cells to support it. Between the Hodenkanälchen found a smaller population of non-epithelial cells, these cells are the androgen-producing Leydig cells. The Leydig cells can be used as the producers of androgens be used as paracrine hormones which Sertoli cells to be needed for the production of sperm to support it. Soon after their differentiation begin the Leydig cells, androgens to form the Maskulinisierung the evolving male fetuses are needed (including the formation of penis and scrotum). Under the influence of androgens are remnants of the Urniere mesonephros, which Wolff's corridors, the epididymis epididymis, vas deferens deferent duct and the seeds of bubbles. This effect of androgens is a hormone made by the Sertoli cells AMH supports the development of embryonic Müller courses to Eileitern and other tissues of the female reproductive system in male embryos prevented. AMH and androgens act together and allowing the normal migration of the testicles into the scrotum.

Before the formation of the Pituitary LH through the embryo, which some in the eleventh to twelfth week, promotes human chorionic gonadotropin (hCG) the differentiation of Leydig cells and the formation of androgens. The Androgenwirkung in the target tissues often involves the conversion of testosterone to 5α-dihydrotestosterone (DHT).