Bronchial epithelium 
Mucus 
Pericellular 
fluid 
Figure 1.9.2-A. Major cell types of the bronchial wall. The epithelium is 
pseudos tratif ied , with all cells resting on the basement membrane. The 
major cell types include ciliated cells, goblet cells, serous cells, undif- 
ferentiated columnar cells, and basal cells. The branched tubular struc- 
tures comprising the submucosal glands are lined with serous and goblet 
cells. The basement of the airway epithelium glands is contiguous with that 
of the airway epithelium. Mucus is produced by the goblet and serous cells 
on the airway epithelial surface and in the mucus glands. Typically, the 
lumen of the submucosal glands are filled with mucus. Above the airway 
epithelium, the airway epithelial lining layer consists of a lower phase of 
pericellular fluid and upper phase of mucus. In the normal lung, the mucus 
layer is discontinuous, forming "islands" resting on the airway surface. 
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Recombinant DNA Research, Volume 16 
