Epithelial proliferation and development of rugae in relation to palatal shelf elevation in the mouse.

Regional variations in epithelial thickness and proliferation have been examined in the palatal processes immediately prior to shelf elevation in mouse embryos. In general, epithelial thickness and mitotic activity is greater on the lateral than on the medial surface of the process. In addition, epithelial thickenings, corresponding in number and arrangement to the rugae characteristic of the adult mouse palate, are present on the lateral surface before elevation. Where they develop, mitotic activity per unit surface length is locally increased. These regional variations in growth and form may augment the intrinsic shelf force.