SYNTHESIS OF EARLY-PREGNANCY FACTOR USING RED DEER (CERVUS-ELAPHUS) AS A DELAYED IMPLANTATION MODEL

Purpose: This study measured serum early pregnancy factor (EPF) in pre gnant red deer (Cervus elaphus) and ascertained whether EPF synthesis is associated with implantation. Methods: Serial serum samples were ta ken from mated hinds up to 42 days postconception and analyzed for EPF activity using the rosette inhibition rest. EPF activity was then cor related with calving records and stages of preimplantation development . Results: EPF was detected in all pregnant animals, with a twin pregn ancy giving increased EPF activity. Three animals gave an EPF response following fertilization but failed to continue beyond the preimplanta tion embryo stage. The increase in EPF synthesis previously associated with implantation in other mammals occurred at the blastocyst stage i n red deer. Conclusions: EPF synthesis in red deer (Cervus elaphus) is consistent with the preimplantation period, as occurs in other mammal s. However, the second phase of the biphasic increase in early pregnan cy factor production is associated with blastocyst formation, not impl antation.