Dziadek M, Dixon K E
J Exp Zool. 1975 May;192(2):285-91. doi: 10.1002/jez.1401920219.
In X. laevis embryos injected with (3-H) thymidine between early gastrula and late neurula, the presumptive primordial germ cell nuclei were labelled and some were observed in mitosis, confirming that division occurs throughout this developmental period. In all labelled and mitotic cells, the germ plasm adjoined the nucleus, an observation which invalidates the hypothesis that germ plasm inhibits mitosis in presumptive primordial germ cells after gastrula. In embryos which had been irradiated with UV at the vegetal pole at the 2-cell stage, the presumptive primordial germ cells also incorporated (3-H) thymidine and divided during the same developmental period.
在早期原肠胚到晚期神经胚阶段注射了（3-H）胸苷的非洲爪蟾胚胎中，推测的原始生殖细胞核被标记，并且观察到一些处于有丝分裂状态，这证实了在整个发育阶段都会发生分裂。在所有标记的和处于有丝分裂的细胞中，生殖质毗邻细胞核，这一观察结果推翻了关于生殖质在原肠胚形成后抑制推测的原始生殖细胞有丝分裂的假说。在二细胞期用紫外线照射植物极的胚胎中，推测的原始生殖细胞也摄取了（3-H）胸苷并在相同的发育阶段进行分裂。
