Search

42 hour-old chick embryos receive intraencephalic injections of a radioactive Actinomycin D solution. The autoradiographic study of the embryonic head after treatment shows that the injected solution remains in the encephalon. In order to avoid some diffusion of the solution in the surrounding territories, it is necessary to take care of the encephalic inner pressure. These experiments allow to a better approach of studying the influence of Actinomycin D upon the embryonic head morphogenesis.

Comparison of results obtained by SCHOWING (1968) with those of BALLIF (1985) shows that frontal bones of chick embryo, which are completely missing after removal of the anterior encephalic territories, are still partially existent after a localized microinjection of Actinomycin D into the embryonic encephalon. The remaining part of frontal bones corresponds to territories mainly derived from the neural crests (NODEN, 1982). These latters don't need any encephalic induction to develop into ossification centres.