Fig. 2. Proliferation, morphology and apoptosis in juvenile Ovol1^-/- testis. (A,B) BrdU labeling of testis from P14 wild-type (A) and Ovol1^-/- (B) mice. Arrows indicate seminiferous tubules that contain multiple rows of BrdU-positive germ cells. Arrowheads indicate the labeled Leydig cells. (C-J) PAS staining of testis from control (wild-type or Ovol1^+/-) (C,E,G) and Ovol1^-/- (D,F,H-J) mice at P14, P16 and P21. E/MP, early/mid-pachytene spermatocytes; DP, diplotene spermatocytes. (I) High-magnification image of the boxed area in H. Black arrowheads in F,I,J indicate apoptotic cells intermingled with late-pachytene spermatocytes or more advanced germ cells. (K,L) TUNEL assays on wild-type (K) and mutant (L) testis from 21-day-old mice. Scale bar: 80 µm in A,B; 35 µm in C-H,J; 9 µm in I; 100 µm in K,L.