The sperm mitochondrion: Organelle of many functions.

This review summarizes current research in sperm mitochondrial function with specific emphasis on mitochondrial metabolism, reactive oxygen species production and mitochondrial genomics. This organelle is key in many crucial sperm functions including motility, hyperactivation, capacitation, acrosome reaction, and fertilization, thus its role in male fertility cannot be ignored. Recent studies have further elucidated sperm metabolism, placing greater emphasis on the importance of mitochondrial energy production for some species. Additionally, the dogma of mitochondrial reactive oxygen species production is changing and is being described by some as an indicator of increased mitochondrial function, potentially representing the most fertile sperm. Further, the mitochondrial genome, specifically mitochondrial DNA copy number, has been indicated as a potential biomarker for sperm quality and fertility in several species. Methods to study the sperm mitochondria are also evolving, allowing for researchers to learn more about the bioenergetics and status of this important organelle. Because of the importance of mitochondrial function for sperm function in most species, it is crucial to better understand the mechanisms involved in order to improve our knowledge of sperm physiology as well as improve handling and storage techniques for the industry.