Vigier B, Prépin J, Jost A
Arch Anat Microsc Morphol Exp. 1976;65(2):77-101.
The chronology and the modalities of the differentiation of the genital apparatus were studied in 187 calf fetuses whose insemination age was exactly known (between 32 and 110 days). Male. In the male, the first seminiferous cords form around days 41-42, the interstitial cells appear 2 or 3 days later. From days 60-70 on, the rete testis is made of tubules with an open lumen, which connect the seminiferous cords. The masculinisation of the external genitalia begins as early as day 47 by a rapid increase of the anogenital distance: on day 60, the penis opens under the umbilicus and the scrotum is well differentiated. The regression of the Müllerian ducts starts at the level of their anterior (tubal) part on day 50, when their diameter decreases. From day 58 on, the oviducts become discontinuous and they are almost completely absent by day 63; the uterine horns and the vagina have dissappeared by day 80. The masculinization of the internal genitalia occurs during two phases: 1) between days 56 and 58: the early buds of the seminal vesicles and of the prostate appear, as well as the first differences at the level of the urogenital connections and of the Cowper's glands; a supra-urethral diverticulum develops at the level of the posterior prostatic urethral flexure; the non sexual urethra remains short. 2) After day 70 take place: the differentiation of the epididymides the branching of the seminal vesicles and the stabilization of the Wolffian ducts (after a transitory diminution of their diameter between days 60 and 80). Female. In the female, sexual organogenesis proceeds later than in males. The Müllerian ducts (which show a transitory reduction of their diameter at their tubal level between days 50 and 60) develop steadily after day 60 at the level of their uterine horns and of the vagina; simultaneously the non sexual urethra lengthens rapidly. A suburethral diverticulum, which is absent in the male, develops at the level of the urogenital connections, between days 60-70. The regression of the Wolffian ducts takes place after day 70 when the mesonephros disappear; they first become discontinuous in their median part (at the uterine level) between days 77-80, but important remains of these ducts still persist on day 110, in the posterior part of the vagina. The first primordial ovarian follicles form only after day 100 approximately.
对187头授精年龄确切已知（32至110天之间）的小牛胎儿的生殖器官分化的时间顺序和方式进行了研究。雄性。在雄性中，最初的生精索在第41 - 42天左右形成，间质细胞在2或3天后出现。从第60 - 70天起，睾丸网由具有开放管腔的小管组成，这些小管连接生精索。外生殖器的男性化早在第47天就开始了，肛门与生殖器之间的距离迅速增加：在第60天，阴茎开口于脐下，阴囊已充分分化。苗勒管的退化在第50天从其前部（输卵管）部分开始，此时其直径减小。从第58天起，输卵管变得不连续，到第63天几乎完全消失；子宫角和阴道在第80天消失。内生殖器的男性化分两个阶段发生：1）在第56至58天之间：精囊和前列腺的早期芽出现，以及泌尿生殖连接处和考珀腺水平的最初差异；前列腺后尿道弯曲处出现尿道上憩室；非性尿道仍然很短。2）在第70天之后：附睾分化、精囊分支以及沃尔夫管稳定（在第60至80天之间其直径有短暂减小之后）。雌性。在雌性中，性器官发生比雄性晚。苗勒管（在第50至60天之间其输卵管水平直径有短暂减小）在第60天之后在子宫角和阴道水平稳定发育；同时非性尿道迅速延长。在泌尿生殖连接处，在第60 - 70天之间出现男性所没有的尿道下憩室。沃尔夫管在第70天之后随着中肾消失而退化；它们首先在第77 - 80天之间在中间部分（子宫水平）变得不连续，但在第110天，这些管道的重要残余部分仍存在于阴道后部。最初的原始卵泡大约在第100天之后才形成。
