CHANGES IN LIPIDS AND MEMBRANE ANISOTROPY IN HUMAN SPERMATOZOA DURINGEPIDIDYMAL MATURATION

Previously it was demonstrated that immature and immotile human sperma tozoa from the caput epididymides developed a good progressive motilit y after in-vitro stimulation with phosphatidylcholine (PC), In order t o define the role of PC and membrane anisotropy in epididymal maturati on and to determine the exact lipid composition of human spermatozoa d uring epididymal maturation, spermatozoa from seven epididymides from patients who underwent orchiectomy because of prostatic cancer were in vestigated, Lipids were determined by highperformance thin-layer chrom atography and gas chromatography, Membrane anisotropy was measured by fluorescence polarization. The ratio between PC and phosphatidylserine (PS) plus phosphatidyl ethanolamine (PE) plus sphingomyelin (SM) was significantly higher in spermatozoa from the cauda compared to those f rom the caput and corpus, This was due to an increase of PC and a decr ease of the concentration of PS plus PE plus SM, With regard to fatty acids, those with saturated chains predominated in caput spermatozoa w hile the highest concentration of unsaturated long-chain fatty acids w as in cauda spermatozoa, A lower membrane anisotropy of cauda spermato zoa compared with caput or corpus spermatozoa was found, In conclusion , during epididymal maturation human spermatozoa integrate lipids, par ticularly PC, which is strongly associated with the induction of progr essive motility, A change in the pattern of fatty acids and a decrease in the cholesterol/phospholipid molar ratio cause a decrease in membr ane anisotropy in cauda spermatozoa.