Our lesion was felt to fit the latter picture. Epithelial odontogenic tumors are rare in rats. Our experience with Lewis rats is limited. The submitters are grateful for the consultation of Dr. Dubielzig, Univ. of Wisconsin, in the interpretation of this lesion. The Department of Oral Pathology reviewed this case and commented that this tumor most closely resembles human odontoameloblastoma, which is very rare.
Teeth develop from two embryonic tissues.
The enamel cap is derived from the dental lamina, an invagination of buccal cavity squamous epithelium. All other parts of the tooth, including dentine, cementum, and pulp, derive from embryonic mesenchyme. Dental epithelial and mesenchymal anlage exhibit inductive influence on each other. The ameloblastic epithelium induces differentiation of the dental papilla mesenchyme into odontoblasts, which form dentine. Dentine then induces ameloblasts to form enamel.