The effect of Mycoplasma hominis and Ureaplasma urealyticum on hamster egg in vitro penetration by human spermatozoa.

The effects of some genital mycoplasmas on the in vitro penetration of human spermatozoa into the master egg were studied. Ureaplasma urealyticum serotypes 4, 8, and 6 showed high interfering activity: 6.3% (P less than 0.01), 12.3%, and 14.5%, respectively, against the 55.6% penetration rate of untreated sperm. Neither a cytotoxic effect of mycoplasmas on gametes nor a masking of the binding sites on the egg surface were demonstrated. In experiments carried out with U. urealyticum serotype 4, the production of diffusible relatively heat-labile factor(s) responsible for the inhibition of sperm penetration was postulated.