In utero cleft lip repair in the mouse without an incision

In utero cleft lip repairs were done by full-thickness approximation of the cleft edges by 11-0 sutures in the A/J mouse on day 17 of gestation after Dilantin was administered on day 10. On day 20, a cesarean section was performed, the repair inspected, and the lip sectioned for histologic study. One-thousand one-hundred and thirty-nine mice were bred, and surgery was performed on 48. At least one fetus was present that had a cleft lip in 21 mice, and repairs were done on 16 fetuses. Ultimately, 9 viable fetuses were studied. In all cases, lip continuity was present where the suture had coapted the edges. There was little or no evidence of the lip repair despite no incision being performed. Histologic examination revealed epithelial and mesenchymal continuity with an occasional notch noted in the epithelium and soft-tissue asymmetry in complete clefts. The implications of these findings are discussed.