Functional gametes derived from explants of single blastomeres containing the "germ plasm" in Xenopus laevis: a genetic marker study.

Single blastomeres containing the "germ plasm" were isolated from 32-cell embryos of Xenopus albino (ap/ap) or wild type and cultured in vitro until the corresponding normal control embryos reached the neurula stage. The resulting explants from albinos were implanted into wild-type host neurulae and vice versa. The formation of functional gametes, eggs or sperm, of donor type was tested when the operated host embryos had reached sexual maturity. The color of the eggs laid by the experimental females and the presence or absence of melanophores in the epidermis and of pigment granules in the eyes of hatched larvae from matings of the experimental males with albino females made possible the identification of donor-type gametes. Twelve males and 12 females of the wild-type hosts, and 16 males and 14 females of the albino hosts survived. Six animals produced donor-type eggs or sperm, most of them being germ line chimeras. This shows that functional gametes can develop from explants derived from single blastomeres containing the "germ plasm."