Fine structure of spermatozoa retrieved from retrograde ejaculates.

The proportion of viable, motile spermatozoa retrieved from retrograde ejaculates has been consistently low. Electron microscopic studies of spermatozoa of retrograde ejaculates collected in Baker's buffer and washed in Ham's F10 medium supplemented with 2% human serum albumin revealed considerable ultrastructural lesions to the sperm head and the midpiece. Swelling and/or loss of plasma membrane was observed in most of the sperm. In others, the membrane continuity was disrupted, and tattered remnants of it remained attached to a grossly abnormal acrosome. The acrosomal cap in the majority of the spermatozoa was swollen and irregular in shape. Some of the spermatozoa lacked the acrosome, and the sperm heads of these were lined by the inner acrosomal membrane. Subcellular derangement in the midpiece of retrograde spermatozoa was characterized by mitochondrial swelling and lysis, indicating definite cytotoxic injury to the spermatozoa. These EM observations are consistent with the findings of high sperm wastage in semen from men with retrograde ejaculation.