ULTRASTRUCTURAL MORPHOMETRY OF SPARSELY GRANULATED PROLACTIN CELL ADENOMAS OF THE HUMAN PITUITARY

Abstract

Fifteen sparsely granulated prolactin-producing adenomas and 10 non-tumorous adenohypophyses, removed by surgical hypophysectomy from patients, were studied using morphometry at the EM level. Compared to non-tumorous prolactin cells, sparsely granulated adenomatous prolactin cells showed a significant decrease in diameter and vol density of secretory granules and an increased vol density of rough-surfaced endoplasmic reticulum and Golgi apparatus. The vol density of mitochondria remained unchanged. The cells of the adenoma are in a highly active functional state. It appears that the equilibrium between hormone synthesis, storage and release is altered in adenomatous prolactin cells.