Abstract

Sperm lipids are important for sperm viability, maturity and function. This study aimed to identify cholesterol and desmosterol composition of human spermatozoa of two sperm populations separated on Sil-Select gradient. Forty-eight males were divided into four groups namely healthy men (n = 13), asthenozoospermia (n = 11), asthenoteratozoospermia (n = 10) and oligoasthenoteratozoospermia (n = 14). Sperm cholesterol and desmosterol were estimated in two human sperm population separated by centrifugation in a discontinuous Sil-Select gradient. The results showed that cholesterol and desmosterol were the major sterols in human spermatozoa. Spermatozoa recovered from upper/lower layer interface (fraction I) had low fertilization potential, while those from the base (fraction II) had high fertilization potential. Median values of cholesterol and desmosterol in fraction I were 2.55 micromol and 0.77 micromol/10(9) spermatozoa and in fraction II were 1.16 micromol and 0.27 micromol/10(9) spermatozoa. Cholesterol/desmosterol ratio was significantly higher in fraction II than I (4.8 vs. 3.2, p < 0.01). Cholesterol, desmosterol, total phospholipids and sterols/phospholipids were negatively correlated with sperm concentrations, sperm motility, linear velocity, normal sperm morphology and acrosome reaction percentage whereas cholesterol/desmosterol ratio was positively correlated with these parameters. It is concluded that the difference in sterol composition of sperm subpopulations separated on Sil-Select gradient suggests that composition of sterols is related to sperm functions.