Ultrastructural evidence of gonadotrophin release from castration cells following injection of LHRH in the rat.

To examine the morphological evidence of the nature of hormone release from castration cells the author gonadectomized neonatal male and female rats. Twenty-eight days after the operation the animals were pretreated with estrogen, progesterone, or estrogen and progesterone in combination, every other day for one week, and then injected with LHRH 30 min before sacrifice. The administration of LHRH elevated remarkably the serum levels of gonadotrophins (LH and FSH) of neonatally gonadectomized rats. The steroid-pretreated animals showed higher serum levels of gonadotrophins than controls. Simultaneously, active exocytosis of secretory granules was observed in the hypertrophic gonadotrophs or castration cells of neonatally gonadectomized and steroid-treated rats following the injection of LHRH. These results indicate that hypertrophic gonadotrophs or castration cells also release hormone(s) by exocytosis of secretory granules.