[Immunohistochemical study of the appearance of somatotropic hormone in the adenohypophysis of chick embryos].

The differentiation of somatotropocytes was studied in the Leghorn chick embryos during 11 to 18 days of incubation and in chickens during the first week of life using the immunohistochemical method of nonlabelled antibodies with PAP complex and antiserum against human somatotropic hormone (STH). Unlike in humans, the fixation of pituitaries in the Carnoy mixture is optimal for STH to be immunohistochemically estimated in the chickens and chick embryos. STH was found in adenohypophysis from 12-13 days of development. Besides predominant localization of somatotropocytes in the adenohypophysis caudal lobe, individual STH-positive cells are also present in the cephalic lobe of chickens and chick embryos. The results obtained suggest a relatively late appearance of STH during histotypical development of adenohypophysis in chick embryos.