| Popis: |
In the seminiferous epithelium of adult nonprimate mammals, so-called A-single (As) spermatogonia are the stem cells of spermatogenesis (1–3). Upon division of the As spermatogonia, the daughter cells either migrate away from each other and become two new stem cells, or the cells stay together becoming A-paired (Apr) spermatogonia connected by an intercellular bridge. About half of the stem-cell population normally divides to form Apr spermatogonia, whereas the other half goes through self-renewing divisions, thereby maintaining stem-cell numbers (Fig. 5.1). |
