Germ-cell transfer and sex ratio in Xenopus laevis

ABSTRACT Primordial germ cells have been grafted from one neurula to another in Xenopus laevis by means of the technique of Blackler & Fischberg (1961). A nuclear marker enabled tadpoles derived from graft material to be identified, after surviving animals had been raised to sexual maturity and bred. The examination of sex ratio in groups of tadpoles has revealed that male gonocytes were sex-reversed in ovaries and vice versa, with eventual production of functional gametes. About half of all transfers made involved grafts between neurulae of unlike sex. It is evident that females of genetic constitution WW are viable in this toad, as well as sperm of constitution W.