Spermatogenesis revisited. V. Spermiogenesis in mice homozygous for two different male-sterile mutations (ps and hpy).

In male mice homozygous for both ps and hpy, two recessive, pleiotrophic, mutations, gametogenesis is normal through meiosis but no functional spermatozoa are produced. Spermiogenesis is abnormal from the Golgi phase on. The types of abnormalities seen during the early and mid-stages of spermiogenesis are characteristic of those associated with the presence of the ps mutation whereas those associated with the hpy mutation appear during the later stages of spermatid development. While centriolar ultrastructure was normal, axonemal structures were only rarely encountered and no late spermatids with recognizable flagella were seen. Some late spermatids showed head abnormalities of the type characteristic of the ps mutation while others were recognizable as being of the hpy type. A released "gamete" usually consisted of a distorted nucleus and associated acrosome enclosed in a tightly fitting plasma membrane. No spermatids exhibiting a novel phenotype were encountered. The findings support the view that, despite their simultaneous presence in the double homozygote, each mutation acts autonomously. These studies also allow a similar inference to be made with respect to the extent of the interrelationship of the other major sub-processes of spermiogenesis.