The ultrastructure of the anterior pituitary gland of the vole, Microtus agrestis, in normal and experimentally manipulated animals.

The ultrastructural appearance of the various types of cell present in the anterior pituitary of the vole has been described. There was a great measure of similarity between the cytological picture in this species and in the rat. Prolactotrophs contained the largest secretory granules, which were of variable shape; the granules of somatotrophs, whilst only slightly smaller than those of prolactotrophs, were invariably round, and of more uniform size; corticotrophs were represented by cells which were extremely angular, and whose secretory granules, besides being smaller than those of somatotrophs, were arrayed around the periphery of the cell below the plasma membrane; gonadotrophs contained granules of a similar size to those found in cortiocotrophs, but were found throughout the cytoplasm of the cells, whic were round to ovoid in shape; thyrotrophs contained the smallest granules of all, the shape of the cell itself bein angular...