McLaren A
Symp Soc Exp Biol. 1984;38:7-23.
The female pathway of germ cell development is characterized by early entry into meiotic prophase, before birth in the mouse. This pathway is followed by all germ cells in the ovary and in the mesonephric region of the urogenital ridge in female embryos, and by all germ cells in the adrenals of both sexes. The male pathway, with meiosis delayed until well after birth, is taken by all germ cells within the testis cords, all or almost all of those within the testis but outside the cords, and most of those in the mesonephric region. Results of culture and co-culture experiments are described. No conclusive evidence has yet been obtained to discriminate between the hypothesis that all germ cells spontaneously enter meiosis before birth unless prevented from doing so, and the alternative hypothesis that germ cells only enter meiosis under the inducing influence of somatic cells. The pathways of development that radiate from an egg cell all lead to a state of terminal differentiation, with the single exception of the pathway that leads to another egg cell. This pathway is capable of cyclic repetition, even without the intervention of a fertilizing sperm: if a normal mouse embryo is aggregated with one derived from a parthenogenetically activated egg, the parthenogenetic component may contribute to the oocyte population as well as to all other cell types examined (Stevens, 1978).
雌性生殖细胞发育途径的特点是在出生前就进入减数分裂前期。在雌性胚胎中，卵巢和泌尿生殖嵴中肾区域的所有生殖细胞，以及两性肾上腺中的所有生殖细胞，都遵循这一途径。雄性生殖细胞的途径是减数分裂延迟到出生后很久，睾丸索内的所有生殖细胞、睾丸内但在睾丸索外的所有或几乎所有生殖细胞，以及中肾区域的大多数生殖细胞都遵循这一途径。文中描述了培养和共培养实验的结果。目前尚未获得确凿证据来区分两种假说：一种假说是所有生殖细胞在出生前都会自发进入减数分裂，除非受到阻止；另一种假说是生殖细胞只有在体细胞的诱导影响下才会进入减数分裂。从卵细胞衍生而来的发育途径都导致终末分化状态，唯一的例外是通向另一个卵细胞的途径。即使没有受精精子的干预，这条途径也能够循环重复：如果将正常小鼠胚胎与孤雌激活卵衍生的胚胎聚集在一起，孤雌生殖成分可能会对卵母细胞群体以及所有其他检查的细胞类型做出贡献（史蒂文斯，1978年）。
