INFLUENCE OF ACTINOMYCIN-D ON THE DEVELOPMENT OF THE EMBRYONIC CHICK ENCEPHALON .2. HISTOLOGICAL STUDY OF THE ANTERIOR NERVOUS TERRITORIES AND OF THE EYES

Actinomycin D in solution is injected into the encephalic vesicle of 42 hours-old chick embryos. Ten days after treatment, a histological study of the anterior nervous territories show various alterations. The olfactive region is little affected, and fails in a group of embryos without upper beak (group 3). The diencephalon shows mainly defects of its infundibular zone, the hypophysis is reduced and sometimes missing. The eyes are generally microphthalmic, but they seem macroscopically normal in group 4. In this latter, the optic retina is altered. In all groups, the optic nerves are always missing, while lenses and pigmentary retinae are more or less developed. The generative layer of the optic retina is the most affected. All these results are in relation with the state of neuropore, they are constant for each group.