FIG. 16.

Spermatogenesis is abnormal in sir2α null mice. Testes from both wild-type (a) and sir2 null (b to e) mice were examined for histopathological abnormalities. At low power, the seminiferous tubules in the wild-type mouse appeared almost uniform in size, while those of the sir2α null mice varied in size and contained large vacuoles in the basal epithelium (arrows). At higher power, significant abnormalities were seen in the testes from sir2α null mice: acrosomal sharing in round spermatids (arrow, c); distorted residual bodies (arrowhead, c); larger-than-normal round spermatids (arrows, d); abnormal retained elongated spermatids (c, asterisks); and numerous vacuolated spaces (asterisks, e). Sections were stained with periodic acid Schiff-hematoxylin. Bars: 100 μm (a and b); 50 μm (c to e).