Preimplantation murine embryos are more resistant than human embryos to bacterial endotoxins

Bacterial endotoxins have been correlated with increased fragmentation of early cleavage-stage human embryos and decreased pregnancy rates in human in vitro fertilization programs. The purpose of the present study was to test the direct effects of increasing concentrations of endotoxins on in vitro fertilization and development of mouse embryos to the blastocyst stage. Sexually mature B6D2F1 female mice were superovulated and oocytecumulus complexes were collected from the oviducts and randomized into control and treatment groups. Oocytes (n = 867) were inseminated with capacitated sperm. Treatments included Ham's F-10 supplemented with 3 mg/ml bovine serum albumin and increasing amounts of endotoxin (0.35, 0.64, 0.92, 1.5, 2.08, 3.21, 6.07, and 11.79 ng/ml). Percentage cleavage, percentage fragmentation at the four-cell stage, and percentage expanded blastocyst formation (of cleaved embryos) were evaluated. Statistically significant decreases in cleavage at 6.07 ng/ml (P less than 0.05) and blastocyst formation at 11.79 ng/ml (P less than 0.05) of endotoxin were observed. Fragmentation at the four-cell stage was significantly increased at 3.21 ng/ml (P less than 0.05) of endotoxin. We conclude that the levels of endotoxin necessary to decrease murine preimplantation development significantly is higher than that reported for human embryos.