Intrauterine repair of a lesion resembling cleft lip and its effect on maternal behavior in rats.

Two studies were done to determine the ideal day to perform an intrauterine procedure and to explore maternal behavior toward repaired cleft lip offspring rats. The first study showed that the best time to create a surgical cleft lesion was on the 19th day of pregnancy. Thus, for the second study rat fetuses were operated in utero on the 19th day of gestation, and the pups were delivered by cesarean section. One group was obtained with a lesion resembling cleft lip and a second group with repair of such lesion. Nonoperated litter mates were used as a control group. Two animals of each type were placed inside a cage, and the order in which the mother retrieved them and carried them to the nest was noted. Statistical analysis showed that retrieving them was not at random. All controls and 14 out of 18 treated animals were retrieved, but only 4 out of 18 of the clefted group were retrieved.