Germ cell chimerism: absence in parabiotic frogs

Embryos of the leopard frog deprived of primordial germ cells by treatment with ultraviolet light were joined in parabiosis with normal, unirradiated embryos. The irradiated member of the pair was not colonized by germ cells from its normal partner. Unlike the primordial germ cells of birds and mammals, the germ cells of frog embryos are not carried by the circulating blood.