[Dynamics of development of the interstitial tissue and seminiferous tubules in the testis of human fetuses].

Morphological changes in the testis of human fetuses (period of embryogenesis--from 8 to 28 weeks) during their differentiation were studied by histological and morphological methods. Investigations carried out demonstrated that complete cycle of transformation in the intestitial and embryonic tissue of the fetal testis could be divided into two main periods: the first period was attended by a gradual increase in the count and differentiation of Heydig's cells in the interstitial tissue (from the 8th to the 12th week of embryogenesis); gradual involution of Leydig's cells in the interstitial tissue and development of seminiferous tubules prevailed during the second period (from the 15th to the 28th week of embryogenesis). In the course of prenatal development of the human fetus testis Leydig's cells passed through a number of successive stages, each one being characterized by a definite functional activity level of these cells. The detected changes in the testes were apparently connected both with the changes in the Leydig's cells count and their functional activity, and with progressive growth of the tubules.