Sperm morphology: consistency of assessment of the same sperm by different observers

Photographic slides of 36 sperm were shown to a group of 28 observers with different lengths of experience in assessing sperm morphology. Experienced observers were generally consistent (10 or more of the 17 agreeing) in classifying sperm as normal, amorphous, small heads, lacking acrosomes, and having tail defects or cytoplasmic droplets but categorization was more variable for large, tapering and pyriform heads. This study highlights the need for more widespread agreement about definition of sperm shapes and the development of practical objective methods of assessment.