Significance of sperm bacteriology for the in vitro fertilization of human and mouse oocytes.

The mouse oocyte was used to determine whether T-mycoplasma or Escherichia coli affects the fertilization and embryonal development of oocytes. Ureaplasma urealyticum (T-mycoplasma) in the mouse oocyte system had little influence on the fertilization rates achieved in vitro; however, in all the experiments there was a marked reduction of embryonal development after in vitro fertilization (IVF) of spermatozoa infected with Ureaplasma. Even in oocytes incubated with Ureaplasma only after having reached the two-cell stage, there was reduced development into blastocysts. Changes in the Ureaplasma concentration and incubation time had no major influence on the development into blastocysts. During IVF of mouse oocytes with spermatozoa infected with E. coli concentrations of 10(3)/mL, there were no changes in the fertilization or culture rate as compared to the control group. However, after insemination with 10(6) bacteria/milliliter there was no change in the IVF rates in the mouse oocyte; however, the culture rates were considerably reduced (19.5% as compared to 64.4% in the control group). Whether there are additional changes in the pregnancy rate after the transfer of blastocysts obtained after insemination of oocytes with infected spermatozoa remains a matter for future investigation.