Body weights, testis weights, and numbers of testis-resident somatic cells of Cstf2t−/− mice do not differ from wild type mice, but numbers of round spermatids are significantly diminished. Male mice ranging in age from 88 to 136 dpp were used in this study. A) Body weights (in grams) of wild type (WT, black bars), Cstf2t+/− (HET, dark gray bars) and Cstf2t−/− (KO, light gray bars) mice (not significant). B) Testis weights (in milligrams) of wild type, Cstf2t+/− and CSTF2T−/− mice (P = 0.0028). C) Numbers of resident somatic cells per testis. Left, number of Leydig cells (not significant); right, number of Sertoli cells (P = 0.0193). D) Numbers of germ cells per testis. From left to right: spermatogonia (not significant), primary spermatocytes (P = 0.0167), secondary spermatocytes (P = 0.0007), and round spermatids (P < 0.0001). Values with the same letter indicate measurements that were not significantly different after ANOVA and a Tukey post-test.