Some aspects of the kinetics of emiocytosis in prolactin cells.

Some aspects of the kinetics of emiocytosis of secretory granules were investigated in pituitary prolactin cells of lactating female rats. Most of the emiocytotic events were directed towards those areas of the cells which were covered with a basal lamina. Diameters of the secretory granules within the emiocytotic pockets and of the openings of the pockets to the exterior were measured. An inverse relationship between the size of the granule and the diameter of the foramen was noted. A mechanism is proposed relative to the processes involved in the release of secretory granules from prolactin cells.