Histogenesis of Squamous Metaplasia in the Hamster Tracheal Epithelium Caused by Vitamin A Deficiency or Benzo[<italic>a</italic>]pyrene-Ferric Oxide

Abstract

In the hamster tracheal epithelium, both vitamin A deficiency and multiple intratracheal instillations of benzo[a]pyrene-ferric oxide caused squamous metaplasia. By light microscopy, squamous metaplasia without cell atypia caused by vitamin A deficiency is morphologically similar to that caused by carcinogen administration. However, significant differences at the ultrastructural level were observed. Defects in the basement membrane, enlarged nuclei with cytoplasmic invaginations, and pleomorphic nucleoli were restricted to squamous metaplasia induced by benzo[a]pyrene-ferric oxide.