Figure 6.

Transmission electron microscopic analysis of the morphology of club cells before and after infection. Transmission electron microscopy was used to quantify the morphological type and frequency of epithelial cells in the respiratory tract of wood mice. (a) Bronchiole. In mock-infected wood mice, the common type of club cell morphology vastly predominated with numerous electron-dense secretory vesicles in the apical part of the cell (arrow). (b) Bronchiole. A proportion of club cells, particularly in the bronchioles of MHV-68-infected wood mice at day 14 p.i. exhibited a distinct morphology with marked vesiculation of the apical part or all of the cytoplasm (arrows) and vesicles containing moderately electron-dense material characteristic of mucin (arrowheads). (c) The proportion of types of club cells in the airways was determined by enumeration of cell types present in electron micrograph images. (d) The proportion of ciliated and non-ciliated cells in the airways was determined by enumeration of cell types present in electron micrograph images.