Ultrastructure of growth hormone-producing cells of rat pituitary after injection of hypothalamic extract.

Abstract

The effects of intracarotid injection of hypothalamic extracts on the ultrastructure of pituitary growth hormone (GH)-producing cells are reported. Male rats were killed 15, 30 and 90 min after injection of hypothalamic extract. After 15 min the secretory granule content of pituitary GH cells was similar to that of nonstimulated glands. However, the release of granules into the perivascular spaces was greatly increased. The releasing phenomenon was still present 30 min after the injection; at this time a prominence of the endoplasmic reticulum as well as of the Golgi apparatus was also noticed. At 90 min the release of secretory granules was reduced to a normal rate; numerous lytic bodies were present. The number of secretory granules seemed to be within a normal range. The relevance of these morphological findings to the understanding of the action of hypothalamic extracts on the GH cells is discussed. (Endocrinology 83: 1278, 1968)