Sam68 is required for male fertility. (A) Analysis of the fertility phenotype of Sam68+/− (n = 5) and Sam68−/− (n = 6) mice. Mice were bred for 5 mo with wild-type females of proven fertility. Females were changed each time they remained pregnant or after 2.5 mo without remaining pregnant. (B and C) Ovulation was induced in wild-type females by hormonal treatment before mating with Sam68+/+ (n = 3), Sam68+/− (n = 3), and Sam68−/− (n = 3) males. Mating was confirmed by observation of the vaginal plug 15 h later, and oocytes were collected from the oviducts 18 h after mating. Fertilization was scored by monitoring formation of the pronuclei (indicated by arrowheads in B) in the fertilized eggs. A graph showing the results of three independent mating experiments is shown in C. Data are represented as the mean ± SD; knockout spermatozoa never fertilized oocytes; SD = 0 in three experiments. *, P = 9.45 × 10−8 in the t test; ANOVA test yielded P < 0.001. (D) Histological analysis of testis from adult mice. Low (left) and high magnification (right) are shown. Arrows indicate round spermatids (r. spt) and elongated spermatids (e. spt) that are dramatically decreased in the Sam68 knockout testis. (E) Profile of propidium iodide–stained purified germ cells from testes of Sam68 wild-type or knockout mice at 25 dpp of age. Peaks corresponding to 1C, 2C, or 4C DNA content are indicated. Quantitative data of the percentage of each germ cell type from three independent experiments are shown in F (data are represented as mean ± SEM). *, P < 0.01 in a t test. Bars: (B) 50 µm; (D) 100 µm.
