DEFICIENCY IN FERTILIZATION BY MORPHOLOGICALLY ABNORMAL SPERM PRODUCED BY AZH MUTANT MICE

Male mice homozygous for the azh mutation produce spermatozoa with abn ormal head shapes and have significantly reduced fecundity, to between 5% and 10% that of wild-type or heterozygous mice. Several possible c auses of this infertility were investigated. No gross endocrine disord ers in azh/azh male mice were observed, and they exhibited apparently normal mating behavior. In addition, their sperm were motile, were cap able of hyperactivated motility, and did not show premature acrosome r eactions. However, quantitative analysis revealed slight but significa nt reductions in several motility parameters. Analysis of embryos foll owing mating of azh/azh males with superovulated females indicated a r eduction in the number of fertilized eggs compared to control matings. In vitro, spermatozoa from azh/azh mice failed to fertilize cumulus-i ntact/zona-intact and cumulus-free/zona-intact ova, although they succ essfully fertilized zonafree ova. These results indicate that the prim ary defect in fertility of azh/azh male mice is a result of sperm qual ity, likely, in sperm morphology, and is manifest at the level of inte raction with the zona pellucida. (C) 1994 Wiiey-Liss, Inc.