Preparation and observation methods can produce misleading artefacts in human sperm ultrastructural morphology

The aim of this study was to evaluate the production of artefacts during preparation and observation of human sperm for ultrastructural morphology and analyse the possible reasons of causing these artefacts. Under the scanning electron microscopy, damaged sperm heads (crack or/and rupture), necks (head-neck or head-midpiece separation) and midpiece (disassembled and denuded axoneme ultrastructures, bent midpiece) were analysed to be the consequence of exogenous effects. Thirty infertile men with teratozoospermia revealed more spermatozoa with damage to head, neck and midpiece than did thirty fertile males (p < .01). After the samples from fertile males underwent five repeated observations, most sperm heads and necks in the samples were destroyed when compared with the single observation (p < .01). Destroyed sperm heads were full of cracks and peelings, even sperm tails were broken and fragmented, and separations of the sperm head-neck or head-midpiece became common. Spermatozoa from fertile males with centrifugation of 600 g for washing sperm exhibited more damage to the midpiece than those with the 300 g (p < .01). These results demonstrate that preparation and observation methods can damage sperm ultrastructures, leading to producing artefacts of ultrastructural morphology. The artefacts of sperm ultrastructural morphology may be associated with sperm structural fragility, preparation conditions and electron beam damage.