Similar ultrastructural defects were found in the spermatozoa of two oligospermic men attending a subfertility clinic.
The majority of spermatozoa had a mid-piece of grossly abnormal morphology and the diameter of the tail was increased, due to an excess of outer-sheath fibres. Extra, as well as missing, axial-filament fibres were also seen. In both cases, only a very small proportion of the spermatozoa were motile.
A testicular biopsy was performed on each man and although the histological appearance was normal, abnormal spermatozoa were seen in thin sections examined by electron microscopy.