EMBRYOGENESIS ABOARD SHUTTLE STS-29

Fertile chicken eggs (Gallus gallus domesticus), 16 containing 2-d emb ryos and 16 containing 9-d embryos, were exposed to a microgravity env ironment during a 5-d space shuttle flight (Discovery, STS-29, March 1 989). The 9-d flight group embryos continued their incubation to hatch at 21-d, revealed no gross abnormalities, and developed normally to a dults. Embryos of the 2-d group did not survive the 5-d mission. Synch ronous controls for both age groups survived, hatched, and developed t o adults. This result supports an hypothesis that a gravity field fact or acts in the cellular and/or intercellular microenvironment during t he development interval 2-7-d in the chick embryo.