论文部分内容阅读
在性染色体构成为XY的8周龄的人胚中,原始生殖细胞已移行于未分化间充质中的两个成对的局限区,即所谓生殖嵴,在此区发生睾丸的分化。此后,胚胎已分化的睾丸产生抑制女性化的物质,导致男性内、外生殖器的发生,在适当的时候,睾丸环境中的生殖细胞就有精子发生。与此相反,当性染色体构成为XX时,在未分化生殖嵴内发生卵巢的分化,那里没有胚胎睾丸的影响,因而发育为女性生殖器,在这种卵巢环境中的生殖细胞就有卵子发生。因此,性别二态性的决定性事件是性腺的二态性,有一条Y染色体就发生睾丸。各种性发育异常与性染色体失衡的人核型/表型之间的关系,提示Y染色体紧邻着丝粒的区段有睾丸分化必需的位点。自分子细胞遗传学诞生以来,人们一直努力探寻该假设性的位点,最近往往把它称为睾丸决定因子
In 8-week-old human embryos with sex chromosome XY, the primordial germ cells have migrated to two paired localized areas of undifferentiated mesenchyme, the so-called genital ridge, where testicular differentiation occurs. Since then, embryos have differentiated testes produce feminine substances, resulting in the occurrence of male and external genitalia, where appropriate, testicular germ cells have spermatogenesis. In contrast, when sex chromosomes are configured as XX, ovarian differentiation occurs in undifferentiated genital ridge where there is no embryonic testes and develops into female genitalia in which germ cells have an egg. Therefore, the decisive event of gender dyness is the gonadal dichotomy, with the testis occurring on a Y chromosome. The relationship between various sexual dysplasias and human karyotypes / phenotypes of sex chromosome imbalance suggests that sites adjacent to the centromere in the Y chromosome have sites for testicular differentiation. Since the birth of molecular cytogenetics, there has been an ongoing search for this hypothetical site, which has recently been referred to as the testis determinator