Influence of cleft palate on growth of the maxilla in mouse embryos.

Cortisone acetate (7.5 mg on day 12, or 4 X 2.5 mg on days 12-15) and single dose of 6-aminonicotinamide (0.5 mg on day 14) were administered to pregnant females of random bred strain H-Velaz mice. The width of the alveolar arch of the developing maxilla was measured in drawings of the roof of the mouth of 600 fixed embryos taken between days 16 and 19. The width of the maxilla of experimental embryos with a closed secondary palate was the same as in the control embryos throughout the observation period, whereas the maxilla of all embryos with cleft palates was wider than in the controls. Final expansion of the maxilla was the same in all experimental groups.