[Early differentiation of supporting cells of the convoluted seminiferous tubules in man (ultrastructural manifestations)].

By means of the electron microscopy method, testes of the human fetuses 6--9 weeks of the intrauterine development (the period, when the gonadal structure differentiates according to the sex) have been studied. In 6--7-week-old fetuses the anlages of the convoluted seminiferous tubules are formed, most of the cells being the supporting ones. They adjoin the basal membrane, while the germ cells do not contact with it and are divided from the latter with a thin processes of the supporting cells cytolasm. Already at early stages of the gonad formation according to the masculine type, many supporting cells form specific processes with a long thin peduncle and a pin-like dilatation at the end. They are situated, as a rule, in the intercellular spaces, sometimes--project into the cytoplasmic recess of the neighbouring supporting cell. These structures have common structural features with the tubulobulbar complexes occurring among the supporting cells of a mature testis. Since in the fetus there is no spermatogenesis, the formation mentioned should be considered as a morphological manifestation of specific differentiation of the supporting cells.