AMELOBLASTOMA IN A FEMALE WISTAR RAT

A spontaneous ameloblastoma of the right mandible is described in a 12 0-week-old female Wistar rat (strain Chbb: THOM). The tumour had a loc ally aggressive growth pattern and was histologically characterized by sheets and islands of odontogenic epithelium bounded by a palisaded l ayer of ameloblast-like cells. Because of multifocal keratinizing squa mous metaplasia of the stellate reticulum tissue, the tumour was class ified as an acanthomatous ameloblastoma. Cyst formation, areas of stro mal hyalinization and enamel matrix-like inclusions were further chara cteristics of the neoplasm. The epithelial elements stained strongly p ositive for broad spectrum cytokeratins.