Levels of cholesterol and phospholipids in freshly ejaculated sperm and Percoll-gradient-pelletted sperm from fertile and unexplained infertile men.

Cholesterol and phospholipid levels were determined in individual sperm samples obtained from 20 fertile and 20 unexplained infertile men. The determination was performed on both washed freshly ejaculated sperm and Percoll-gradient-pelletted sperm. Although sperm cholesterol levels in unexplained infertile patients were significantly lower, i.e., 10.6 +/- 1.3 (mean +/- SD) nmol/10(7) freshly ejaculated sperm and 5.4 +/- 0.7 nmol/10(7) Percoll-gradient-pelletted sperm as compared with 19.9 +/- 1.9 nmol/10(7) and 12.6 +/- 1.5 nmol/10(7) for corresponding sperm populations in fertile donors. Motility parameters measured in 10 sperm samples of the two groups of fertile and unexplained infertile men revealed increases in the amplitude of lateral head displacement and decreases in percent of straightness in sperm tracks from unexplained infertile men.