The =ureters= are the narrow part of the excretory ducts of the kidneys.
Each begins at the renal pelvis and terminates at the bladder. It is
about ⅓ to ¼ inch (ca. 6 to 8 mm.) in diameter, and its average length
is about 28 inches (ca. 70 cm.). The =abdominal part= (Pars abdominalis)
of each ureter emerges ventrally from the hilus of the kidney, and
curves backward and inward toward the lateral face of the posterior vena
cava (right side) or the posterior aorta (left side). They then pass
almost straight backward in the subperitoneal tissue on the surface of
the psoas minor, cross the external iliac vessels, and enter the pelvic
cavity. The =pelvic part= (Pars pelvina) passes backward and a little
downward on the lateral wall of the pelvic cavity, turns inward, and
pierces the dorsal wall of the bladder near the neck.
In the male the pelvic part enters the urogenital fold and crosses the
vas deferens. In the female the ureter is situated in the greater part
of its course in the dorsal part of the broad ligament of the uterus.
The wall of the ureter is composed of three coats. The outer =fibrous
coat= (Tunica adventitia) is composed of loose fibrous tissue. The
=muscular coat= (Tunica muscularis) consists of inner and outer layers
of longitudinal fibers, with a stratum of circular fibers between them.
The =mucous membrane= (Tunica mucosa) is covered with transitional
epithelium; glands (Glandulæ mucosæ ureteris) resembling those of the
renal pelvis occur in the first three or four inches of the ureter.