Ontogenesis of the LH-RH-containing neuronal elements in the hypothalamus of the rat.

LH-RH-containing neuronal elements were detected earliest in the median eminence and in the vascular organ of the lamina terminalis of newborn rats. The peroxidase-labeled antibody method was used. Since the synthesis of the gonadotrophic hormones starts already on the 18th day of intrauterine life in the rat, this finding does not support the view that LH-RH could have inductive effect on the differentiation of the gonadotropic cells of the anterior pituitary gland.