Fig. 1. Size and histology of testes from p53^+/- control (C) and Brca1^/p53^+/- mutant (M) mice. Ages of mice are indicated. (A,D,G,J,M) Control mice; (B,E,H,K,N) Brca1 mutant mice. No significant difference in size was detected between control and mutant testes at postnatal day 10 (P10); however, mutant testes are smaller at P16 and older. Arrows indicate spermatozoa (A), diplotene spermatocytes (G), round spermatocytes (J) and differentiated spermatids (M). Mutant testes lack these cells. Arrowheads in H,K,N indicate condensed nuclei, which are TUNEL positive (see Fig. 3).