Abstract

Electron microscopic examination of the non‐granulated cells of the adenohypophysis of several species has evidenced a unity of structure amongst vertebrates. Efforts to correlate structure and function have been made, but they have often been hampered by the scarcity or absence of direct experimental methods for the investigation of their function. Yet often the evidence in favor of a given role has been circumstantial, relying on coincidences between changes in the secretory activity of the gland and changes in the ultrastructure of the non‐granulated cells or in colloid production. At the present time, the prevailing hypothesis is that, in addition to a possible role in mechanical support within the gland, the non‐granulated cells seem to be important with respect to the secretory process of the endocrine cells and/or to the metabolism of the adenohypophysis.