Fig 2. Tooth model initial conditions.

A, B, Depiction of the model initial conditions as frontal (A), and sagittal (B) sections. The cells lining the border of the epithelium (cells in green) and the uppermost layer of suprabasal cells are fixed in space, representing the physical barrier imposed by the oral epithelium surrounding the base of the tooth germ. The space under the mesenchymal layer however, is empty, allowing the tooth germ to grow in depth, bucco-lingually and antero-posteriorly. C-E, The three hypotheses raised as different distributions of cell proliferation in the different tissues, frontal sections shown. Non proliferative cells have been darkened. Blue: enamel epithelium. Yellow: Suprabasal layer. Purple: mesenchyme. Red: enamel knot.