Human ameloblastomas in vitro: light microscopical and ultrastructural observations.

The light microscopical and ultrastructural morphology in vitro of one case each of human plexiform, follicular and acanthomatous ameloblastoma are described. Ultrastructural analysis of cultured tumour cells revealed that the main cell type growing in vitro displayed morphological features typical of columnar cells or preameloblast-like cells of ameloblastomas. Irrespective of histological type all cases showed indistinguishable in vitro light microscopical and ultrastructural morphology. These findings strongly suggest that the columnar cell type accounts for the main proliferative capacity of ameloblastomas in vitro and most likely also in vivo.