Mitochondria and fertility: the mitochondria critical role on spermatozoa function

Mitochondria of spermatozoa significantly differ, structurally and functionally, from the corresponding orga- nelles of somatic cells. Nevertheless, sperm mitochondria, as well as the somatic ones, are the location of the ox- idative phosphorylation (OXPHOS) process, which is necessary for the production of metabolic energy in the form of adenosine triphosphate (ATP). In addition to their basic role in oxidative energy generation, mitochon- dria are also a source of reactive oxygen species (ROS), which, at low concentrations, play a physiological role in many sperm processes. It is commonly accepted that a proper functionality of mitochondria is necessary for a high quality of sperm cells; this last parameter, in its turn, is a pre-requisite for a high sperm fertilizing ability. Evaluation of mitochondrial respiratory efficiency represents therefore a valuable test that could integrate routine semen analysis.