In vitro fertilization (IVF) assays using sperm from wild type and SP hyh mice.

Metaphase II eggs from wild type (Napa(+/+)) female mice were incubated with sperm from wild type (Napa(+/+), wt) or mutant homozygous with the slow progressive phenotype (Napa(hyh/hyh), hyh) mice. Following capacitation, sperm from wild type and hyh mice were diluted to 2 or 4×105 sperm/ml and coincubated with eggs from wild type female mice. In experiment “A”, the same number of sperm cells from wt and hyh mice was used (2×105 sperm/ml). In experiment “B” the number of sperm from hyh mice was duplicated (4×105 sperm/ml). (*, p<0.02 or **, p<0.001 for hyh versus wt; Fisher's exact probability test).