Morphological changes of pituitary gonadotrophs and thyrotrophs following treatment with LH-RH or TRH in vitro.

To investigate the relationship between LH-RH and TRH and the formation of castration cells and thyroidectomy cells, pituitary glands of 14-day old female rats were cultured with LH-RH or TRH for 10 days. Observed in these glands were external and internal zones, the former containing active, healthy appearing cells, and the latter consisting of many degenerative and necrotic cells. Gonadotrophs and thyrotrophs were readily demonstrated in the external zone of the organs by immunocytochemistry. Hypertrophic gonadotrophs (castration cells) and thyrotrophs (thyroidectomy cells) were observed only in the external zone by electron microscopy. Neither the typical signet-ring gonadotrophs nor intracisternal granules of thyroidectomy cells were seen in the present study. However, the hypertrophic gonadotrophs or thyrotrophs were similar to castration cells or thyroidectomy cells observed in the pituitary gland following castration or thyroidectomy. The results indicate that LH-RH and TRH directly stimulate the secretion of hormones and alter the morphological features of pituitary target cells.