Autoradiographic study of macromolecular synthesis in the fusion epithelium of the developing rat primary palate in vitro.

The facial processes involved in primary palate formation undergo epithelial fusion in a manner morphologically analogous to that observed during secondary palate formation. We have used whole embryo culture to analyze the synthesis of macromolecules (DNA, protein glycoprotein) in the primary palate, based on the incorporation of various labeled precursors. The results of this study demonstrate that changes in the synthesis of macromolecules occur during the fusion of the facial processes, which resemble those previously reported to occur during secondary palate development. These changes include cessation of DNA synthesis in cells in a restricted zone of the epithelium, concomitant with maintenance of glycoprotein synthesis. These findings indicate that the molecular events underlying the development of the primary and secondary palate may be similar.