Ullmann S L, Shaw G, Alcorn G T, Renfree M B
Department of Zoology, University of Melbourne, Parkville, Victoria, Australia.
J Reprod Fertil. 1997 May;110(1):135-43. doi: 10.1530/jrf.0.1100135.
Primordial germ cells (PGCs) of the tammar wallaby Macropus eugenii have a distinctive morphology and stain positively for alkaline phosphatase. PGCs are identifiable in embryos with 12 somites, on about day 17 of the 26.5 day gestation period, when they are located in all three germ layers of the developing embryo and in the endoderm of the bilaminar and vascular (trilaminar) yolk sac membranes. PGCs are positive for alkaline phosphatase (ALP) at least between days 17 and 22 of pregnancy. In whole mounts on day 17, three groups of cells positive for ALP occur: about 40 just caudal to the neural tube, and about 20 distributed on either side of the last three somites. By day 21, there are about 150 PGCs in the newly formed gonadal ridges and 275 in the mesenteries. On days 21-22, there are PGCs in the umbilical mesoderm, the dorsal mesentery and the coelomic angles between the dorsal mesentery and the mesonephroi. On day 22, most ALP-positive PGCs are located in the dorsal mesentery, where they occur in groups. They apparently do not migrate through the hindgut endoderm, but occasional PGCs are seen in sites such as the mesonephros, the adrenals, the blood vessels of the yolk sac and in the vicinity of the dorsal aorta and dorsal nerve cord. Between day 23 and day 25, 1 day before birth, most of the 3200-4000 PGCs complete their migration to the gonadal ridges. Although there are marked differences between embryogenesis of tammars and mice, development and the pattern of migration of PGCs in this marsupial mammal are similar to that of eutherian mammals.
帚尾袋鼩（Macropus eugenii）的原始生殖细胞（PGCs）具有独特的形态，且碱性磷酸酶染色呈阳性。在妊娠26.5天的第17天左右，胚胎有12对体节时可识别出PGCs，此时它们位于发育中胚胎的所有三个胚层以及双胚层和血管（三胚层）卵黄囊膜的内胚层中。PGCs至少在妊娠第17天至22天之间碱性磷酸酶（ALP）呈阳性。在第17天的整体标本中，出现三组ALP阳性细胞：约40个位于神经管尾侧，约20个分布在最后三对体节的两侧。到第21天，新形成的生殖嵴中有约150个PGCs，肠系膜中有275个。在第21 - 22天，脐中胚层、背系膜以及背系膜和中肾之间的体腔角中有PGCs。在第22天，大多数ALP阳性PGCs位于背系膜中，呈成群分布。它们显然不通过后肠内胚层迁移，但偶尔会在中肾、肾上腺、卵黄囊血管以及背主动脉和背神经索附近等部位看到PGCs。在出生前1天的第23天至25天之间，3200 - 4000个PGCs中的大多数完成向生殖嵴的迁移。尽管帚尾袋鼩和小鼠的胚胎发生存在显著差异，但这种有袋类哺乳动物中PGCs的发育和迁移模式与真兽类哺乳动物相似。
