[The development of urogenital organs after lateral mesoblast heterotopic graft in the toad (Bufo bufo) neurula. II. Simultaneous inversion of anteroposterior and dorsoventral axis of the lateral plate].

Simultaneous inversion of the anteroposterior and dorsoventral axes of the lateral mesoblast in the early toad neurula leads to the total agenesis of the urogenital organs. The experimental results show that the lateral mesoblast is unable to undergo self-differentiation, and that three factors at least are required for the formation of the urogenital blastemata. The mesoblast must be competent: only the posterior (dorsal, but also ventral) part of the lateral mesoderm is endowed with this competence. It must receive two stimulating influences, from the cordomesoblast on the one hand, and from the dorsocaudal endoblast on the other hand.