DISTRIBUTION OF P21(RAS) DURING PRIMARY PALATE FORMATION OF NONCLEFT AND CLEFT STRAINS OF MICE

Cleft lip, with or without cleft palate, is one of the most common def ects in craniofacial formation. The primary palatogenesis of mice is s imilar to that of humans and spontaneous cleft lip is associated with genotype in both mice and humans. To investigate the temporal and spat ial expression of ras genes in cleft (A/WySn) and non-cleft strains of mice (BALB/cBy), a broad spectrum ras antibody was used. Positive sta ining was found in ectodermal, mesenchymal, and neuroepithelial cells of facial prominences before the primary palate formation stage (10 d 20 hr) in both strains. During the primary palate formation stage (11 d 20 hr), positive staining was found in the ectodermal and mesenchyma l cells of the facial prominences of the non-cleft strain but not in t hose of the cleft strain. These results suggest ras genes may play a r ole in the primary palatogenesis of mice. Cleft lip could be associate d with the deficiency of ras gene expression during primary palate for mation of mice.