[Influence of cyclic adenosine monophosphate on the migration of primordial germ cells of the anuran Amphibians (author's transl)].

After the treatment in toto of the embryos from various species of Anura by cAMP, the number of primordial germ cells (PGC) in genital ridges is strongly reduced; the most part of the PGC are found in the endoderm. A ventral implant of agar impregnated with a solution of cAMP attracts numerous PGC in the same way as grafted chordomesoderm. The chordomesoderm itself, incubated with 3'-5' cyclic nucleotide phosphodiesterase, then grafted on to the ventral area of normal embryos attracts very few PBC compared with the non-incubated chordomesoderm. The results are analyzed and discussed along the following hypothesis: the migration of the PGC of the Anura is guided by cAMP which, diffusing from the chordomesoderm, is distributed along a concentration gradient increasing in a ventrodorsal direction. The PGC go up the gradient by a chemiotactic mechanism and reach the dorsal parts of the embryo.