[The development of urogenital organs after lateral mesoblast heterotopic graft in the toad (Bufo bufo) neurula. I. Distinct inversions of anteroposterior and dorsoventral axis of the lateral plate (author's transl)].

Anteroposterior inversion of lateral mesoblast of early toad neurula is followed by differentiation of diverse urogenital blastema, according to the transplant position before the graft. Anteroposterior polarity of lateral mesoderm is thus perfectly determined in young neurula. On the contrary, dorsoventral inversion of lateral mesoblast leads to mesodermic blastema formation according to the transplant position after the graft. Particularly, the dorsal region of the lateral plates displaced to ventral position does not form blastema. On the other hand, the ventral region which shows a dorsal position after the graft develops and produces a typical blastema. Thus, in the young neurula, the dorsoventral polarity is not yet determined in the lateral plate of the mesoblast. Such a result shows also that the ventral and posterior regions of the lateral mesoblast are competent to form blastema. Moreover, factors from dorsal origin and external to lateral mesoblast take part in urogenital organ anlagen formation.