Cauda epididymal sperm were collected via swim-out from 8-week-old males (n = 7 fl/Y ▪; n = 9 cKO/YSox2-Cre). (A) Sperm morphology was assessed by light microscopy. Representative images of difference interference contrast (DIC) display the morphological patterns found indicated by arrows: 1, Head malformation; 2, Coiled midpiece; 3, Flipped head. Scale bar = 25 µm. (B) Quantification of the morphology patterns. Percentages of normal sperm, coiled midpiece, head malformation, and flipped head out of the sperm population. At least 100 sperm per sample were counted, total sperm counted 1146 for fl/Y and 1077 for cKO/YSox2-Cre. Values represent the mean ± s.e.m. (C) Sperm motility was evaluated in the swim-out (T0) and after 60 min of incubation in conditions that support capacitation (T60). Sperm motility was examined using the CEROS computer-assisted semen analysis (CASA) system. Percentage of total motile sperm in the population. n = 12, values represent the mean ± s.e.m. (D) Classification of type of motility (progressive, intermediate, hyperactivated, slow, and weakly motile; in percentage) out of the total motile population at T0. n = 12, values represent the mean ± s.e.m. (E) Classification of type of motility (in percentage) out of the total motile population after 60 min of incubation in capacitation conditions (T60). n = 12, values represent the mean ± s.e.m. (F) Representative images for cleavage and blastocyst stages at 24 hr and 96 hr, respectively. Asterisks indicate embryos not reaching anticipated embryonic stage. Scale bar = 100 μm. (G) Summary of IVF results. n = 142 and 313 presumed oocytes for fl/Y and cKO/Y sperm, 7 and 8 animals, respectively. Values represent the mean ± s.e.m.