Spermatozoon and mitochondrial DNA.

In eukaryotic cells, mitochondria are the major site of ATP production, which is achieved through the electron-transport chain and oxidative phosphorylation, according to the energy demand. Mitochondria contain their own genome (mitochondrial DNA, mtDNA) on which a limited number of genes are encoded. In the human sperm, mitochondria helically wrap the midpiece of the tail and supply the energy for the driving force of motility. While various mutations in mtDNA in somatic cells are found to be associated with a wide spectrum of diseases, it is also reported that the abnormal mtDNA causes astenozoospermia and male infertility. At fertilization, the paternal mitochondria and mtDNA are rapidly degraded early in embryogenesis, thus, only maternal mtDNA is transmitted to the descendant. We briefly review here the basic characteristics of mtDNA and its maternal transmission during fertilization, as well as male infertility. (Reprod Med Biol 2002; 1: 41-47).