An ameloblastoma with myofibroblasts and intracellular septate junctions.

This report represents a review of the ultrastructural features of the simple ameloblastoma. Our ultrastructural data indicate that the stromal component of ameloblastoma is composed of myofibroblasts with associated collagen and basal lamina material. A unique feature of these myofibroblasts is the formation of plaque-like structures on extended cell processes which were identified as intracellular septate junctions. The epithelial component of ameloblastoma was shown to be composed of three distinct cell types which appear to represent a continuum for the ameloblast-like basal cell through an intermediate to an acanthomatous cell. The actual relationship between the three cell types is unclear.