Relationship between sperm morphology and binding capacity to the zona pellucida: a critical step leading to fertilization

Conventionally measured features of semen using the World Health Organization (WHO) criteria1, including sperm concentration, motility, and morphology, all affect rates of fertilization in vitro and the outcome of assisted reproductive techniques, as demonstrated in both IVF (in vitro fertilization) and GIFT (gamete intra-fallopian transfer) therapies2-4. The evaluation of sperm morphology by a more stringent technique (strict criteria) has been shown to enhance significantly the prediction of IVF outcome3,5-7.