A revised model for spermatogonial expansion in man: lessons from non-human primates.

We have recently described a revised scheme for spermatogonial expansion in non-human primates. We proposed that A(pale)-spermatogonia act as self-renewing progenitors and premeiotic germ cells are organized and divide as small clones. Here, we are revisiting the model described for man and propose a modified scheme for spermatogonial expansion. Our revised model shows high similarity to the scheme proposed for non-human primates and is in accordance with all previous and present data.