Sperm of Pih1d3^−/− mice are immotile and morphologically abnormal. (A) Structural representation of four proteins that contain a PIH1 domain. The numbers indicate the amino acid residues that correspond to predicted PIH1 domain regions. (B) Motility of sperm from adult wild-type (WT) and Pih1d3^−/− mice as evaluated by determination of the percentage of motile sperm at 1, 2, and 4 h after release from the cauda epididymis. Two batches of at least 100 sperm were examined for each mouse. Data are means ± SEM (n = 2 batches from one mice). *, P < 0.01 versus the corresponding value for WT sperm (Student’s t test). (C) Movement of 10 WT or Pih1d3^−/− sperm was traced with TEMA software over 5 s. The movement of individual sperm cells is indicated by the different colored lines. Bars, 50 µm. (D) Light microscopy of WT and Pih1d3^−/− spermatozoa collected from the cauda epididymis. Whereas the head of sperm from Pih1d3^−/− males appeared normal, the tail was thinner, shorter, and more susceptible to breakage (arrows) compared with that of WT sperm. Images were obtained with a 40× objective. Bars, 50 µm. (E) Original data for B. (F) Sperm length, the width of the midpiece region, and the frequency of broken sperm are shown for WT and Pih1d3^−/− sperm. The number of samples examined is shown as n.