Male PP1cgamma mutant mice are sterile due to disruptions in spermatogenesis. Previous light microscope studies in our lab have identified key histological features of PP1cgamma mutant testes. The current study employs light and electron microscopy to identify new morphological abnormalities in PP1cgamma mutant seminiferous epithelium.Electron microscopy was used to determine that junctional complexes in PP1cgamma mutants are ultrastructurally normal, and therefore do not contribute to the breakdown in tissue architecture seen in mutants. Electron microscopy also revealed acrosomal defects in PP1cgamma mutants.I have used light microscopy to identify specific stages of spermatogenesis and germ cell types that are affected by the PP1cgamma mutation. This study revealed that some, but not all, germ cells are unable to continue development past stages VII or VIII of spermatogenesis. This causes the depletion, but not complete absence, of elongating spermatids and spermatozoa. Light microscopy also revealed that spermatogonia are depleted in mutants.