Examination for platelet-activating factor production by preimplantation mouse embryos using a specific radioimmunoassay

A specific and highly sensitive radioimmunoassay was used to measure platelet-activating factor (PAF) production by preimplantation mouse embryos in vitro. Levels of PAF greater than 1 pg per embryo were not observed in 24-h culture medium from 2-cell embryos, compacted morulae or blastocysts, or in extracts from these embryos. Synthetic PAF added to embryos at the start of culture could be almost totally recovered after the incubation period, indicating negligible degradation of PAF during culture. PAF was also not detected in embryo samples using a washed rabbit-platelet aggregation assay. It can be concluded that mouse embryos do not produce substantial levels of PAF, or any of the biologically active analogues of PAF detected by the assay.