Variation of cholesterol, phospholipid and triacylglycerol content in subsets of human spermatozoa isolated by density gradient

Objectives: Lipid components of spermatozoa have an important role in its functional activity. In this study the concentration of cholesterol, phospholipid, triacylglycerol and total lipid in different subsets of human spermatozoa, isolated as three fractions by a discontinuous PureSperm gradient, was determined. Methods: Aliquots of the liquefied semen samples (n=107) were layered on top of the upper layer of 40 and 80% PureSperm gradient. The resulting interfaces 40 and 80% (fraction 1), 80% and pellet (fraction 2), and pellet (fraction 3) aspirated and transferred into separate tubes. Lipids were extracted with 6 volumes of chloroform-methanol (2/1, V/V) and the concentration of cholesterol, phospholipid, triacylglycerol were determined by colorimetric method. Results: Percent of sperm with normal morphology was significantly higher in sperm fraction 3 compared to fraction 2 and 1, while percent of sperm with midpiece and tail defect was significantly higher in fraction 1 compared to fractions 2 and 3 (P 0.01). The amount of cholesterol, phospholipid and total lipid of sperm fractions 2 and 3 were about 1.5-fold higher than that of found in sperm from fraction 1 (P 0.05). Conclusion: This result suggests that the total lipid contents of sperms increase with increasing normal morphology from fraction 1 to 3.