Electron microscopic localization of glycoproteins in pituitary cells of duck and quail.

Abstract

Structures demonstrating the presence of glycoproteins, acid phosphatase activity and OsO4 impregnation were localized by means of the electron microscope in duck and in quail pituitary cells. Two methods for the electron microscopic demonstration of glycoproteins were used: a chromic acid-phosphotungstic acid mixture on glycol-methacrylate-embedded tissues, and the periodic acid-thiocarbohydrazide-silver proteinate technique. Both methods showed glycoproteins in the following sites: ( a) the secretory granules in three types of cells (A, B, C) which are part of the seven different cells of the avian pituitary; ( b) the several kinds of dense bodies which are richer in reaction product than the secretory granules. A correlation with previous studies on similar species of birds is helpful in identifying each of the three positive types of cells as thyrotropic cell (A), prolactin cell (B) and gonadotropic cell (C). The presence of glycoproteins within the Golgi saccules (on condensing granules) was found with the periodic acid-thiocarbohydrazide-silver proteinate method in these gonadotropic cells only. In gonadotropic and thyrotropic cells, acid phosphatase activity is weak in the inner Golgi saccules and strong in the "Golgi Endoplasmic Reticulum Lysosomes" system, in the lysosomes, in the dense bodies and in the vacuolated dense bodies. The structures which are richest in glycoproteins are also those which have the most acid phosphatase activity. On the contrary, OsO4-stained structures in duck gonadotropic cells (nuclear pericisterna, rough endoplasmic reticulum, cisternae and outer Golgi saccules) have no glycoproteins or acid phosphatase activity.