In-vitro maturation of immature human male germ cells

Both meiotic and postmeiotic maturation events have been observed to occur in human male germ cells during in-vitro culture. The temperature of 30 deg rees C, medium supplementation with follicle-stimulating hormone and testos terone and the maintenance of the original cell-cell associations within ex planted segments of the testicular seminiferous tubules are common features of the most efficient culture systems. The in-vitro maturation processes a re markedly accelerated as compared to the in-vivo situation, probably due to the abrogation of a checkpoint controlling the full assembly of molecule s needed for spermiogenesis. Moreover, both meiotic and postmeiotic maturat ion processes can be reactivated in vitro in some cases with a complete blo ck of the same processes in vivo. Healthy babies were born after micromanip ulation-assisted fertilization with in-vitro matured elongated spermatids f rom men with complete in-vivo maturation arrest at the round spermatid stag e and at the primary spermatocyte stage. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.