FIG 2.

Mechanisms associated with Ureaplasma species-induced infertility in men. A number of mechanisms have been proposed to account for the clinical observational studies showing decreased fertility among men who experience urethral colonization with Ureaplasma spp. These include (i) cross-reactivity of host-generated antibodies against the UreG protein of Ureaplasma spp. to the autoantigenic sperm protein; (ii) the generation of toxic compounds, such as reactive oxygen species (ROS), which contributes to lipid peroxidation, DNA fragmentation, and subsequent apoptosis; (iii) direct binding to spermatozoa, which may result in reduced motility; and (iv) reduced incorporation of P34H and hyaluronidase activity in the acrosomal cap, which may reduce the capacity of spermatozoa to penetrate the egg.