IN-VITRO EFFECTS OF SOME DIFFERENTIATION INDUCTORS IN METAPLASTIC EPITHELIUM OF THE HUMAN NASAL CAVITY

The alterations in the mucociliary unit in the course of chronic infla mmation of the upper respiratory tract correspond to morphologic anoma lies of the respiratory epithelium and induce cuboidal and squamous me taplasia. While the squamous pattern is most probably irreversible, it is still not clear whether it is possible to restore ciliogenesis in cuboidal metaplasia. In the present study, the action of different ind uctors of differentiation was evaluated in vitro in isolated cells and explants from human nasal metaplastic epithelium. Polar/apolar compou nds induced secretory activity, whereas retinoic acid was able to indu ce ciliogenesis in some cases. Therefore, the cuboidal metaplastic con dition appears to be reversible, and two distinct pathways of differen tiation, secretory and ciliogenetic, are identifiable.