Studies of the fine structure of ovarian interstitial tissue

Summary The fine structure of the thecal gland of the domestic fowl, is described for the first time. In the fowl, the glands are located as islets of lipid-laden cells in the theca interna and also in the interfollicular regions. They appear as well defined structures, organized like endocrine glands, quite different from the surrounding theca interna cells. Each gland is composed of two different cell types, the steroid-producing cell, and a cell type never described before, named the enclosing cell. Both cell types are surrounded by a common, distinct basal membrane. The steroid-producing cells are characterized by their content of organelles typical of steroid-producing cells in other organs. The enclosing cells are char cterized by their peripheral location within the gland and their membranous contact with the steroid-producing cells, long processes with desmosomes and their relation to the nerve fibers. They do not contain the organelles typically found in steroid-producing cells. So far, the real function of the enclosing cells is unknown. The following structures are demonstrated in ovarian steroid-producing cells of the fowl for the first time: cytoplasmic microtubules and filaments, intramatrical lipid-like droplets, attachment devices, the polarity of the steroidproducing cells of the thecal gland.