Journal of Reproduction and Development
Online ISSN : 1348-4400
Print ISSN : 0916-8818
ISSN-L : 0916-8818
Research Notes
Detection of Early Pregnancy Factor in the Sera of Cows Whose Uteri were Infused with Trophoblastic Cell Culture Medium
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1998 Volume 44 Issue 1 Pages 91-94


The aim of this study was to examine whether or not uterine infusion with a medium showing positive early pregnancy factor (EPF) activity influences maternal physiology in cattle. Trophoblastic cells derived from 12-day-old bovine embryos were cultured in Dulbecco's PBS (+) at 39 C in air for 24 h. EPF activity was assayed using the rosette inhibition test. A rosette inhibition titer (RIT) above 4 was regarded as indicating positive EPF activity. The trophoblastic cell culture medium (Tro-CM) showed positive EPF activity. On days 7 to 12 after estrus, five cows each received a nonsurgical infusion of Tro-CM (0.25 ml) in the lumen of the uterine horn. Blood samples were collected daily by the tail artery or vein puncture from day 0 (the day of infusion) to day 5. All five cows showed positive EPF activity in their sera on days 2 to 4, and three cows out of the five kept showing positive EPF activity for 2 to 3 days. The result demonstrated that sera of cows infused with a small amount of EPF-positive medium (Tro-CM) into the uterus showed temporary positive EPF activity in maternal serum, further suggesting that EPF released from Tro-CM would induce a release of maternal EPF, but not by directly entering into the maternal blood flow.

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