Spermatogenesis revisited

Abstract

Male mice homozygous for the recessive p-locus allele p ^s are sterile. Spermatogenesis is normal through the completion of meiosis, but is abnormal from the Golgi phase of spermiogenesis on. During acrosome formation various abnormalities appear, ranging from atypical Golgi-acrosome complexes to multiple acrosome “implantation” sites on the spermatid nuclei. In many developing acrosomal caps the distribution of acrosomal material is irregular. During the nuclear elongation phase, bundles of microtubules oriented parallel to the manchette have been seen lying in cylindrical invaginations of some spermatid nuclei. In later spermatids, chromatin condensation appears to proceed normally but may be unduly delayed in reaching completion. These various perturbations give rise to a wide spectrum of abnormal spermatozoa ranging from spermatozoa with heads of near-normal morphology to highly bizarre heads which have lost their chromatin. Sperm flagellar ultrastructure is normal and all sperm tails; even those devoid of recognizable heads, are highly motile. These findings support the view that the development of the sperm head is under the control of a group of genes distinct from those mediating events involved in flagella development.