Control of interferon-tau secretion by in vitro-derived bovine blastocystsduring extended culture and outgrowth formation

A series of experiments was conducted to examine the pattern of interferon- tau (IFN-tau) secretion by bovine blastocysts during extended culture in vi tro. In the first experiment, blastocysts were cultured individually for th ree 48-hour periods. The day of blastocyst formation affected how much IFN- tau was produced during the first two culture periods, but not during the t hird period. The overall secretion of IFN-tau during the 6-day period incre ased significantly and well beyond what could be accounted for by the conco mitant increase in cell numbers. In the second experiment, blastocysts were initially cultured in individual droplets for 48 hr, then plated into 48-w ell plates. Medium concentrations of IFN-tau were determined after 48 hr an d again after 6 and 12 days of culture. Initial IFN-tau secretion did not a ffect the ability to form outgrowths or their final size, and initial diffe rences in secretion between groups of blastocysts had disappeared by the se cond and third analyses. In the third experiment, blastocysts were cultured individually for 48 hr in droplets containing the medium that had been flu shed th rough the uteri of non-pregnant sheep on days 10, 12, and 15 of the estrous cycle. Culture in the medium obtained from the Day 15 flush signif icantly increased the number of cells that blastocysts contained, as well a s IFN-tau secretion. (C) 2001 Wiley-Liss, Inc.