Page 724 - Atlas of Histology with Functional Correlations

lamina propria (2). The muscularis exhibits an inner longitudinal layer (3)

and a middle circular muscle layer (4). A third outer longitudinal layer (not
shown) is added to the wall in the lower third of the ureter, near the bladder. A
connective tissue adventitia (6), with blood vessels (5) and adipose tissue (7),
surrounds the ureter.

FIGURE 18.16 ■ Ureter (transverse section). Stain: iron hematoxylin and
Alcian blue. ×10.

FIGURE 18.17 | Urinary Bladder: Wall

(Transverse Section)

The bladder has a thick muscular wall that is similar to that of the lower third of
the ureter. In the wall are found three loosely arranged layers of smooth muscle,
the inner longitudinal, middle circular, and the outer longitudinal layers.
However, as in the ureter, the distinct muscle layers are difficult to distinguish.

The three layers are arranged in anastomosing smooth muscle bundles (1)
between which is found the interstitial connective tissue (2). In this illustration,
the muscle bundles are sectioned in various planes (1), and the three distinct
muscle layers are not distinguishable. The interstitial connective tissue (2)

merges with the connective tissue of the serosa (3). Mesothelium (3b) covers
the connective tissue of the serosa (3a) and is the outermost layer. Serosa (3)
lines the superior surface of the bladder, whereas its inferior surface is covered
by the connective tissue adventitia, which merges with the connective tissue of

adjacent structures.

The mucosa of an empty bladder exhibits mucosal folds (5) that disappear

723