The functionality of mitochondria differentiates human spermatozoa with high and low fertilizing capability.

By using flow-cytometric sorting, we compared some of the major factors related to fertility in sperm subpopulations with high and low mitochondrial membrane potential (DeltaPsi(m)). Results demonstrate that DeltaPsi(m)(high) spermatozoa represents a subpopulation of sperm with high fertility performance because they have normal morphology, high motility values, and calcium ionophore-induced acrosome reaction, suggesting the importance of mitochondrial functionality for fertilizing capacity of human spermatozoa.