Lung - Regeneration

Lung, Bronchiole - Regeneration in a male Wistar Han rat from an acute study. A single, thin layer of flattened epithelial cells covers the bronchiolar surface.
Figure 1 of 3

Lung, Bronchiole - Regeneration in a male Wistar Han rat from an acute study. There is a single layer of flattened epithelial cells on the bronchiolar surface; the cell debris (arrow) in the bronchiolar lumen suggests epithelial damage.
Figure 2 of 3
comment:
Regeneration is the process whereby denuded portions of epithelium-lined surfaces (i.e., airways and alveoli) are repaired. Once the epithelium becomes necrotic or ulcerated, the adjacent, viable epithelial cells replace the lost cells. In the airways, the process begins with elongation of the adjacent epithelial cells, which become flattened, and migration of these cells across the wound to cover the basement membrane ( Figure 1


recommendation:
Lung - Regeneration should be diagnosed whenever present and evidence of necrosis or degeneration is also present. If the number of epithelial cells exceeds that which would be considered within normal limits, hyperplasia should be diagnosed, regardless of whether it is a direct effect of test article exposure or excessive regeneration, but the pathogenesis of the hyperplasia should be discussed in the pathology narrative. A site modifier (e.g., bronchus, bronchiole, alveolus) should be included in the diagnosis to indicate the location of the lesion. Regeneration should not be graded. To convey the severity of the lesion, either necrosis or degeneration must be diagnosed concurrently and graded (see Lung, Epithelium - Degeneration and Lung, Epithelium - Necrosis). Other associated lesions, such as inflammation, should be diagnosed separately. If the pathologist judges that the regenerating epithelium exhibits significant features of atypia, then Lung - Atypia, Cellular should be diagnosed and graded.references:
Boorman GA, Eustis SL. 1990. Lung. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 339-367.
Dixon D, Herbert RA, Sills RC, Boorman GA. 1999. Lungs, pleura, and mediastinum. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 293-332.
Renne RA, Dungworth DL, Keenan CM, Morgan KT, Hahn FF, Schwartz LW. 2003. Non-proliferative lesions of the respiratory tract in rats. In: Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC.
Web page last updated on: December 07, 2015