[Immunohistochemical study of the differentiation of the cephalic lobe of the adenohypophysis in chick embryos].

It was shown by means of indirect immunofluorescence that ACTH appeared in the cephalic lobe of the chick embryo pituitary beginning from the 8th day of the development. A new tissue-specific antigen (A3) is revealed, which is localized in the cephalic lobe of adenohypophysis and becomes manifest at the 7th day of embryogenesis. Quantitative analysis of ACTH and A3 localization in the cells of 11-day chick embryo adenohypophyses allows a conclusion that A3 is localized in corticotropic cells.