Acrosomeless sperm. A cause of primary male infertility.

Sperm without acrosome of two males--spouses of infertile marriages--were studied. No acrosome could be identified in the Papanicolaou stained smears of either patient. Electron microscopy study confirmed the absence of acrosome and post-acrosomal sheath. The physical and functional integrity of the sperm membrane was determined by vital staining technique (72% unstained) and hypoosmotic stress test (69% swollen). Acrosin assay showed a five-fold decrease, and proacrosin values were almost eight-fold lower than the normal values. Nonzymogen acrosin level was normal. Zone-free hamster oocytes were not penetrated by the acrosomeless sperm showing 46% progressive motility, but postcoital tests in both female spouses showed active sperm. The results would indicate that the sperm devoid of acrosome may be considered as a primary cause of male infertility.