In vitro development of palatal tissues from embryonic mice. II. Tissue isolation and recombination studies.

The epithelial and mesenchymal tissues of the secondary palate from 12-, 13-, and 14-day embryonic mice were enzymatically separated and cultured in isolation and in homochronic and heterochronic recombinations. In both homochronic and heterochronic recombinations, epithelial differentiation was similar to that in vivo. In heterochronic recombinations, epithelium differentiated according to a schedule appropriate for the age of the epithelium rather than for the age of the mesenchyme, suggesting that differentiation of palatal epithelium is temporally 'determined' as early as 12 days of gestation. Palatal epithelium cultured in isolation was capable of limited differentiation. Potential for differentiation therefore exists within the isolated palatal epithelium at an early stage of palatal development, and epithelial-mesenchymal interactions are required during palatal development to support full epithelial differentiation.