Some considerations on the human Leydig cell (immunohistochemical observations).

The presence and functional activity of human Leydig cells were assessed at diverse stages of human gonad development in biopsies obtained from healthy controls and subjects with cryptorchidism or varicocele. In our investigation primary antibodies directed against vimentin and testosterone by immunoperoxidase technique of biotin-streptoavidin amplified system were used to analyse immunoreactive sites. The antivimentin antibody is, in general, a specific marker of cells of mesenchymal origin and also detects the presence of Leydig cells, while the antitestosterone antibody shows the functional status of these cells. The immunohistochemical examination revealed the presence of two main populations in the testes of healthy subjects: a foetal and an adult population. The former appeared during the embryonal period, remained throughout foetal life and disappeared after birth. The latter was detected just before puberty and was present for the whole fertile period. Leydig cells in testes affected by cryptorchidism or varicocele showed normal morphology when the disease did not involve intertubular connective tissue. Leydig cells disappeared or were very altered when intertubular tissue was seriously damaged. The intertubular damage was observed in some children with cryptorchidism after prolonged hormonal therapy and in some adults with long term cryptorchidism or varicocele. These observations confirm that if hormonal therapy fails to bring the testis down into the scrotum surgery is required at first years of the life and that in selected cases the varicocele vascular alteration must be surgically corrected.