Are the primordial germ cells (PGCs) in urodela formed by the inductive action of the vegetative yolk mass?

In the present study, when carefully demarcated areas of blastula animal cap were combined with the vegetative yolk mass, PGCs occurred only in those combinations which included the equatorial marginal zone of the animal cap. Furthermore, removal of the vegetative yolk mass as early as stage 6 1/2 did not affect the formation of PGCs. On the basis of these and other observations it is suggested that in urodeles, as in anurans, PGCs may develop from specific cells which nevertheless differentiate into PGCs only when suitable mesodermal elements are formed.