Time-Lapse Relation to Changes in the Respiratory Epithelium after Minimal Trauma

Abstract

(1) A series of changes takes place in the respiratory epithelium in extirpated cow tracheas after a light swab has been passed over the surface. These take place over a period of 1 to 24 hours and are characterized by progressive loosening from one another of the columnar cells and cleavage from the underlying cells, with subsequent loss of cell form and complete exfoliation of the columnar layer. A new surface forms on the remaining cells, giving the appearance of a thin, flat epithelium. (2) During these changes, the epithelium becomes progressively more fragile and even, after just two hours, can usually be wiped away cleanly with a 5-gram swab. (3) The staining of the cells by methylene blue seems to be due to injury of the cell and is not dependent upon the presence or absence of overlying mucin. (4) No definite regeneration of epithelium could be determined in the extirpated trachea, even up to 72 hours, although there were suggestions of it.