[Ultrastructural study of odontogenesis in the frog (Rana temporaria L.)].

Differentiation of the cells of the dental bud which produce the hard tissues of teeth was studied at the ultrastructural level; the activity of these cells (odontoblasts and ameloblasts), the laying down of organic matrices elaborated by them, the mineralization of these matrices, and the maturation of dentine and enamel are described. Injections of tritiated proline enabled us by the autoradiographic method, to confirm and to indicate more precisely the activity of these cells. Dental calcified tissues of Rana exhibit the general properties of these tissues among Vertebrates: high content of apatite, low content of organic materials (collagenous in dentine, non-collagenous in enamel), precise orientation of crystals, and true but non-prismatic enamel. The enamel of Anura as well as enamel of Urodela is a true enamel of epithelial origin.