Respiratory System

Lung - Metaplasia, Squamous

    Narrative
    Lung, Alveolus - Metaplasia, Squamous in a female Harlan Sprague-Dawley rat from a subchronic study. The normal alveolar epithelium has been replaced by squamous epithelium.
    Lung, Alveolus - Metaplasia, Squamous in a female Harlan Sprague-Dawley rat from a subchronic study (higher magnification of Figure 1). The metaplastic epithelium matures normally from basal cells to squamous epithelial cells.
    Lung, Alveolus - Metaplasia, Squamous in a female Harlan Sprague-Dawley rat from a chronic study. The normal alveolar epithelium has been replaced by squamous epithelium, which can be identified by the lakes of eosinophilic keratin (arrows).
    Lung, Alveolus - Metaplasia, Squamous in a female Harlan Sprague-Dawley rat from a chronic study (higher magnification of Figure 3). The metaplastic epithelium is keratinized; there is also hyperplasia of the alveolar epithelium.
    Lung, Bronchiole - Metaplasia, Squamous in a male F344/N rat from an acute study. The normal bronchiolar epithelium has been replaced by squamous epithelium adjacent to an ulcer.
    Lung, Bronchus - Metaplasia, Squamous in a male F344/N rat from a subchronic study. The normal bronchiolar epithelium at the bifurcation of an airway has been replaced by squamous epithelium (arrow).
    Lung, Bronchus - Metaplasia, Squamous in a male F344/N rat from a subchronic study (higher magnification of Figure 6). The normal bronchiolar epithelium has been replaced by squamous epithelium (arrow).
    Lung, Bronchiole - Metaplasia, Squamous, Atypical from a male B6C3F1 mouse in a subchronic study. The cells on the epithelial surface are squamous, but the cells in the deeper layers are disorganized, and there is anisocytosis and anisokaryosis.

    Authors

    Mark F. Cesta, DVM, PhD, DACVP
    Staff Scientist/NTP Pathologist
    NTP Pathology Group
    National Toxicology Program
    National Institute of Environmental Health Sciences
    Research Triangle Park, NC


    Darlene Dixon, DVM, PhD, DACVP
    Group Leader
    Molecular Pathogenesis Group
    National Toxicology Program
    National Institute of Environmental Health Sciences
    Research Triangle Park, NC


    Ronald A. Herbert, DVM, PhD
    Group Leader/NTP Pathologist
    Pathology Support Group
    National Toxicology Program
    National Institute of Environmental Health Sciences
    Research Triangle Park, NC


    Lauren M. Staska, DVM, PhD, DACVP
    Senior Pathologist
    WIL Research
    Hillsborough, NC

    Reviewers

    Gary A. Boorman, DVM, PhD, DACVP, DABT, DACLAM
    Pathologist
    Covance Laboratories, Inc.
    Chantilly, VA

    Robert C. Sills, DVM, PhD, FIATP
    Chief, Cellular and Molecular Pathology Branch
    National Toxicology Program
    National Institute of Environmental Health Sciences, Research Triangle Park, NC