[Progesterone-induced changes in the endometrium. Ultrastructural studies of castrated, adrenalectomized and...

Research has been made on the progesterone-induced effects upon endometrium on impuberal rats (either intact, or castrated, or castrated and adrenalectomized, or hypophysectomized) after an acute or a protracted treatment, which were made every third hour all through the day. It resulted that the hormone basically shows two distinct activities. The first one causes a modest awakening of the anabolical functions both in the lining and in the glandular epithelia, which results in the building up of small amounts of lipid and glycogen. The second one involves the lamina propria as well, and brings about morphological effects which can be superposed on those induced by estrogens. The former seems an autonomous activity and can mainly be found after long-lasting treatments. The latter, on the contrary is influenced by the administration time and can be detected only during a.m. treatments whereas it cannot be detected during p.m. and night treatments. Besides it is influenced by the hypophysal activity and in particular by gonadotropins. The possible mechanism of these influences are discussed.