EMBRYONIC PLATELET-ACTIVATING-FACTOR PRODUCTION IN THE RABBIT INCREASES DURING THE PREIMPLANTATION PHASE

Objective: This study measured platelet activating factor (PAF) produc tion by rabbit embryos in vitro and ascertained if there is increased PAF production associated with advancing embryonic development. Study Design: Two-cell rabbit embryos were recovered from superovulated New Zealand White does and cultured in vitro for 96 hr. Every 24 hr embryo s were scored for development stage and PAF activity from the correspo nding culture medium was measured by platelet aggregation and organic phosphate analyses. Results: PAF was detected in culture medium at all stages from two cells to blastocysts and rose significantly (P < 0.00 1) at each 24-hr interval, reaching maximal levels at the expanded bla stocyst stage. Conclusion: Maximal PAF production by expanded blastocy sts may be an embryonic paracrine signal that facilitates implantation .