Page 726 - Atlas of Histology with Functional Correlations
P. 726
FIGURE 18.18 ■ Urinary bladder: contracted mucosa (transverse section).
Stain: hematoxylin and eosin. Medium magnification.
FIGURE 18.19 | Urinary Bladder: Stretched
Mucosa (Transverse Section)
When fluid fills the bladder, the transitional epithelium (1) changes its shape.
Increased volume reduces the number of cell layers, the surface cells (5) appear
squamous, and the thickness of the epithelium (1) is reduced to about three
layers. This is because the surface cells (5) flatten to accommodate the
increasing surface area. In the stretched condition, the transitional epithelium (1)
may resemble stratified squamous epithelium found in other regions of the body.
Folds in the bladder wall also disappear, and the basement membrane (2) is not
folded. As in an empty bladder (Fig. 18.18), the underlying connective tissue (6)
contains venules (3) and arterioles (7). Below the connective tissue (6) are
smooth muscle fibers (4, 8), sectioned in cross (4) and longitudinal (8) planes.
FIGURE 18.19 ■ Urinary bladder: stretched mucosa (transverse section). Stain:
hematoxylin and eosin. Medium magnification.
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