[Ultrastructure of rat Sertoli and Leydig cells normally and under prolonged internal irradiation].

The ultrastructure of the Sertoli and Leydig cells of rats under conditions of a long-term inner radiation has been studied. The inner radiation (intravenous injection of 75Se-selenomethionine) induced considerable alterations in the ultrastructure of these cells that, in their turn, led to functional changes in the cells. The ultrastructure of the Sertoli and Leydig cells was seen restored in 18 months after an injection of 75Se-selenomethionine. The importance of these alterations in the course of spermatogenesis is discussed.