Tracheal epithelium: cell kinetics and differentiation in normal rat tissue

Publisher Website
Google Scholar
Abstract
The fate of [3H]thymidine ([3H]dTr) pulse-labeled cells was followed in the tracheal epithelium of young male rats. The time course for cell differentiation and the relation of events to tissue composition were studied. In vivo labeling and light microscopic autoradiography of expoxy-embedded sections were used. Labeled and total nuclei for each cell type and combinations of labeled cells which were adjacent to one another were tallied. Hierarchical analyses of variance were performed on the several data sets. All cell types, except ciliated, were labeled at 1 h. A few labeled ciliated cells were seen 24 h post-label. The frequency of labeled intermediate cells peaked at day 2; goblet and ciliated cells, at day 3. No significant changes occurred in the labeling index, but at 24 h the frequency of adjacent labeled cells (ALC) had increased > 5-fold and changes had occurred in patterns of ALC combinations. Labeled ciliated cells seen at 24 h were adjacent to labeled intermediate cells. No labeled basal-ciliated cell combinations were seen at any time. Ciliated cells can develop from S-phase intermediate cells within 24 h. Neither basal nor superficial goblet cells are progenitors of ciliated cells. Apparently, superficial goblet cell and ciliated cell development is preceded by 2 divisions, a basal cell division followed by an intermediate cell division.