Ikenishi Kohji, Nieuwkoop Pieter D
Hubrecht Laboratory, International Embryological Institute, Utrecht, The Netherlands.
Dev Growth Differ. 1978;20(1):1-9. doi: 10.1111/j.1440-169X.1978.00001.x.
The location and ultrastructure of the primordial germ cells (PGCs) were studied in Ambystoma mexicanum larvae of stages 23 to 47. PGCs were found in the spaces between the endodermal cell mass and the lateral plate mesoderm at stages 23 to 35. Some of the PGCs at stage 35, and most of them at stages 40 and 42, were located near the Wolffian duct. At stages 46 and 47 all the PGCs were situated in the genital ridges. Cilia, which have hitherto never been reported in PGCs, were occasionally seen in PGCs of Ambystoma from stage 23 till stage 46. No "germinal plasm" was found in the PGCs prior to stage 40. Specific structures or "nuage material", corresponding to the germinal granules or their derivatives in Xenopus, were first recognized in the vicinity of the nucleus at stage 40. Between stages 40 and 46, the amount of "nuage material" markedly increased. It was finally localized mainly in "intermitochondrial spaces". A possible transfer of material from the nucleus to the cytoplasm or vice versa through nuclear pores was first noticed at stage 40, the material concerned being quite similar in ultrastructure to the "nuage material".
对23至47期的墨西哥钝口螈幼虫原生殖细胞（PGCs）的位置和超微结构进行了研究。在23至35期，PGCs位于内胚层细胞团和侧板中胚层之间的间隙中。35期的一些PGCs以及40和42期的大多数PGCs位于沃尔夫管附近。在46和47期，所有PGCs都位于生殖嵴中。在23期到46期的墨西哥钝口螈PGCs中偶尔可见纤毛，此前PGCs中从未有过关于纤毛的报道。在40期之前，PGCs中未发现“生殖质”。在40期，首次在细胞核附近识别出与非洲爪蟾中的生殖颗粒或其衍生物相对应的特定结构或“云状物质”。在40至46期之间，“云状物质”的数量显著增加。最终它主要定位于“线粒体间空间”中。在40期首次注意到可能存在通过核孔在细胞核和细胞质之间的物质转移，所涉及物质在超微结构上与“云状物质”非常相似。
