[Ontogenesis of the hypothalamo-hypophyseal system. Partial autonomy of the development of the fetal adenohypophysis in the rat]

Abstract

Specific differentiation of the hypothalamus and that of hypophysis has been followed. From day 12 of fetal life the synthesis of hypothalamic LHRH could be demonstrated by radioimmunoassay. The presence of adenohypophyseal LHRH receptors was also evident from day 16 of gestation. Studies on gonadotroph hormone synthesis have revealed that production of LH starts on fetal day 12, while that of FSH appears later, on fetal day 19. In order to study the capacity of hypophysis to differentiate, Rathke's pouches removed on fetal days 11-12 were maintained in organ culture. It has been demonstrated by immunocytochemistry and RIA that hormone production occurs also in cultures pituitaries kept in chemically defined medium (M 199). In sum, these results suggest that hypothalamus factors do not seem to play a determining role in the cytodifferentiation of hypophyseal cells.