The formation of mammalian sperm involves a complex developmental process. In a recent review in the Journal of Lipid Research (1), Simon Horvat at the University of Ljubljana in Slovenia and colleagues discuss the dramatic changes that take place in membrane lipid composition during spermatogenesis.
In particular, the authors focus on cholesterol and its intermediates. They describe sterol dynamics in sperm maturation and explain recent technical advances that could help researchers understand the complex process of sperm formation and function.
Cholesterol and its intermediates are one class of molecules whose content greatly differs between the cells of the male reproductive system and cells of nonreproductive systems. For example, in several mammalian species, cholesterol precursors, such as the testis meiosis-activating sterol and desmosterol, have been observed to accumulate in spermatozoa and testes but not in nongonadal cells.
The enzymes involved in the production of sterols found in the male reproductive system, such as the cytochrome P450 lanosterol 14α-demethylase, show stage-specific expression patterns during the formation of sperm. Studies have indicated that there is complex time- and cell-specific regulation of sterol-compound production during spermatogenesis.
Sterols are also involved in sperm transport. Studies have shown that the epididymal transit of sperm and their movement through the female reproductive tract involves changes in the sterol composition in the spermatozoal membrane that are needed for successful fertilization. Despite all the evidence pointing toward the importance of cholesterol and its intermediates in sperm formation and function, Horvat and colleagues note that the exact role of sterols in the male reproduction system is still unclear.
- Rok Keber, et al. J. Lipid Res. doi: 10.1194/jlr.R032326
Rajendrani Mukhopadhyay (email@example.com) is the senior science writer for ASBMB Today and the technical editor for The Journal of Biological Chemistry. Follow her on Twitter (www.twitter.com/rajmukhop).