Effect of Mycoplasma bovis and Mycoplasma bovigenitalium in semen on fertilization and association with in vitro produced morula and blastocyst stage embryos.

摘要

Frozen-thawed bovine semen contaminated with M. bovis or M. bovigenitalium at either a high (106 CFU/ml) or low (104 CFU/ml) concentration was used for bovine oocyte insemination. The resulting embryos were washed 10 times as recommended by the International Embryo Transfer Society (IETS) before isolation of the agent. A total of 1494 oocytes was inseminated with contaminated sperm cells and 855 oocytes with uninfected control semen. There was a significantly higher proportion of embryos that developed to the blastocyst stage in control than in the mycoplasma exposed groups. Isolation of motile spermatozoa by swim-up procedure before insemination did not render sperm cells free of Mycoplasma spp. Although M. bovis was isolated from all washed embryos after the high exposure level, it was found in only 60% of the samples after the low exposure level. In contrast, M. bovigenitalium was isolated from 70 and 12% of washed embryos exposed to the high and low levels of microorganism, respectively. Using scanning electron microscopy, both microorganisms were detected in association with the surface of zona pellucida-intact embryos and with sperm cells. These results indicate that mycoplasmas present in semen can be transmitted through the IVF system and infect embryos. Furthermore, the experiments showed that supplementation of culture media with standard antibiotics and washing embryos as recommended by IETS were not effective in rendering IVF embryos free from M. bovis and M. bovigenitalium.