Cells of the corpora lutea of albino rats were examined histochemically after the administration of high perogesteron doses at various periods of pregnancy and lactation. Before the prepartum exogenous progesteron failed to influence the fetal development, during the prepartum--led to prolongation of the periods of pregnancy, and by the 25th day--to the intrauterine death of the fetuses in 100% of cases. Progesteron administration during the lactation increased the lactic acid function. Saturation of the organism with exogenous progesteron was accompanied by depression of the secretory activity of the lutein cells without any functional changes in the interstitial cells. Metabolic processes were disturbed in the lutein cells, this being expressed in the interruption of formation of the secretory vacuoles, reduction of the plate complex of Golgi function and a sharp depression of the lipid synthesis. Mitochondria are subject to disintegration. A comparative morphofunctional analysis of the corpus luteum cells under conditions of directed changed hormonal balance confirmed the concept on the separate production of progestins and estrogens by two types of the secretory cells.