Figure 2.

Juvenile Amh-cre;Sin3a^fl/fl testes exhibit a progressive loss of spermatogonia and a block in spermatid elongation.

(A): Cross-sections of 3-wk-old control Amh-cre;Sin3a^+/+ (left) and mutant Amh-cre;Sin3a^fl/fl (right) testes stained with hematoxylin and eosin (H+E). (B): Cross-sections of 3-wk-old control (left) and conditional knockout (right) testes immunostained with anti-GCNA1 antibody. Note the appearance of equivalent numbers of GCNA1-positive germ cells. (C): Cross-sections of 3-wk-old control (left) and conditional knockout (right) testes immunostained with anti-PLZF antibody. The outlines of distinct seminiferous tubules are demarcated with dashed lines (representing basement membranes). Arrow identifies a single PLZF-positive spermatogonium in the field of view. (D): Cross-sections of 4-wk-old control (left) and conditional knockout (right) testes stained with H+E. Arrowheads identify spermatogonia that reside along the basement membrane; small black arrows indicate regions of the basal compartment devoid of germ cells; asterisks denote empty spaces suggestive of where spermatogonia used to reside; pound signs mark the adlumenal compartment where round spermatids exhibit increased cell separation from each other. (E): Cross-sections of 5-wk-old control (left) and conditional knockout (right) testes stained with H+E. Arrowheads identify spermatogonia on the basement membrane; small black arrows indicate regions devoid of germ cells; small yellow arrows denote meiotic spermatocytes that now reside along the basement membrane; pound sign marks round spermatids occupying the basal compartment. Note the absence of elongated spermatids in the Amh-cre;Sin3a^fl/fl testis, and the abnormal-looking round spermatid nuclei with clear zones, indicative of cell degeneration. Scale bars represent 50μm (A–E).