Fig. 6. Morphology and comet assay on sperm isolated from 7-week wild-type and Ercc1-deficient mice. Morphology of (A) wild-type and (C) transgene-positive Ercc1-deficient sperm, note abnormal shapes of sperm heads () and presence of tail abnormalities (^*). Comet assay of (B) wild-type and (D) transgene-positive Ercc1-deficient sperm. Note increased size of comet tails compared with B. (E) Summary of comet assays. At least 200 sperm from four animals of each genotype were scored. The median value for the percentage of the DNA in the comet tail is shown for each sample, along with the median value (black diamond) for each genotype (+/+, wild type; +/-, Ercc1 heterozygote; -/-, transgene-positive Ercc1 deficient). DNA damage was significantly higher (P<0.05 by Mann-Whitney U test) in transgene-positive Ercc1-deficient than wild-type sperm.