Variation in the cholesterol/phospholipid ratio in human spermatozoa and its relationship with capacitation.

The cholesterol/phospholipid (C/PL) ratio was determined for spermatozoa from eight men with normal semen parameters. There was a close correlation between the C/PL ratio and the rate of sperm capacitation as assessed by the hamster egg penetration test. A lower C/PL ratio correlated with a faster capacitation time. This supports the notion that the loss or reduction of membrane cholesterol constitutes an important step of capacitation in human spermatozoa.