Adenosine 3',5'-monophosphate, morphogenetic movements and embryonic neural differentiation in Pleurodeles waltlii

Evidence is presented for the following hypothesis dealing with dibutyryl-c-AMP induction of neural differentiation in Pleurodeles waltlii embryos: (1) Dibutyryl-c-AMP induces the determination for neural differentiation. (2) Additional dibutyryl-c-AMP is not needed for cytodifferentiation. (3) Cytodifferentiation of induced cells can only take place after morphogenetic movements (in vivo) or extensive cell migrations (in vitro). It is suggested that cell migrations, both in vivo and in vitro, lead to the separation of the induced cells from one another or from unidentified inhibitory cells.