[The direct action of actinomycin D upon the encephalon of the chick embryo. Experimental obtainment of cyclopia].

Experimental cyclopia and synophtalmia have been reproduced by the direct action of actinomycin D on the entire embryonic brain at an early stage of development. We excise the brain, treat it with solutions of different concentrations of actinomycin D and replace it in the embryo.We find that with increasing actinomycin concentration, there is a continous progression from the normal embryo to a type lacking a large part of the head. The fronto-nasal process, usually excised and treated, along with the brain, develops only at lower actinomycin concentrations. When it does not develop, fusion of the eyes and synophtalmia are favoured. The maxillary processes always develop, the position of the bones being dependent upon the fusion of the eyes and the development of the fronto-nasal process. It seems that actinomycin D has no effect on the development of the maxillary processes.