Five pregnant rats flown on the biosatellite (embryonic days thirteen to eighteen) were allowed to complete their pregnancies after recovery. These pups and their mothers were then examined in a comprehensive, quantitative study of sensory and behavioral development. A microcomputer system monitored the cages 24 hours/day and recorded (each fifteen minutes) the number and duration of maternal visits to the nest. Pups were inspected each day at the time of weighing to note their general appearance and check for landmark events. Sensory tests were performed to demonstrate the presence of functional responsiveness in selected modalities.

Results:

Four of the flight females had normal deliveries of live offspring postflight. The postpartum cycle of lactation and maternal behavior was displayed by all dams. Olfactory, tactile, and vestibular perceptions were functional at birth. High frequency (40 KHz) auditory detection appeared impaired, and there were signs of possible vestibular supersensitivity. In contrast to data derived from flight animals sacrificed at recovery, the anatomical and functional picture presented by this study suggest that the five day interval between recovery and birth may have constituted an ontogenetically significant period of readaptation to gravity, during which time compensatory alterations in development removed or repaired perturbations exerted by the space environment.