Electron microscope study of two types of cells in the anterior lobe of the Chinese quail adenohypophysis with special reference to their cytological features after photostimulation.

Two types of cells in the adenohypophysis of the Chinese quail, Excalfactoria chinensis, were studied by electron microscopy in birds receiving nine hours of light per day, and birds exposed to continuous light. Type-I cells of photostimulated quail have a well-developed vacuolar system consisting of cisternae and perinuclear spaces confluent with each other. The cytoplasm is restricted to small strands enclosing cell organelles. Secretory granules reaching 150-250 nm in size are scattered at the secretory pole of the cell. Exocytotic vesicles are not often observed. A circular Golgi apparatus with immature secretory granules in its neighbourhood is characteristic for this type of cell. Type-II cells of photostimulated quail present analogous features: distended endoplasmic reticulum and perinuclear spaces. A cup-shaped Golgi apparatus is often observed, with secretory granules, ranging in size from 80-150 nm. Exocytosis is regularly observed. Evidence is provided that the Type-I cell could be a LH-like cell (gamma-cell), and Type II, a FSH-like cell (beta-cell) in birds. The existence of relationships between gonadotrophs and thyrotrophs did, nevertheless, not exclude the possibility that one of the two types could be a thyrotroph.