is a small muscular tubule lined with transitional
epithelium. It carries urine from the renal pelvis to the
bladder. The wall of the ureter is composed of
consists of transitional
epithelium and loose connective tissue (
middle layer, the
, is relatively thick and contains
inner longitudinal and outer circular smooth muscle layers.
These two muscle layers are often difF
cult to distinguish. The
wall of the ureter becomes thicker as it nears the bladder. As
it approaches the urinary bladder, the ureter may also contain
a third layer of smooth muscle. The
layer is com-
posed of connective tissues, nerve F
bers, and blood vessels. It
provides protection, blood supply, and nervous innervation
to the ureter.
Nephrolithiasis (Renal Stones).
) is common in clinical practice.
Symptoms range from vague abdominal pain to renal colic
and hematuria when stones pass from the renal pelvis into the
narrow portion of the ureter. Most renal stones are composed of
calcium salts, calcium oxalate, or calcium phosphate. Other
less common forms include uric acid, magnesium ammonium
phosphate (struvite), and cystine stones. Risk factors for the
development of kidney stones include dietary factors, metabolic
abnormalities, abnormal urine pH, family history of renal stones,
frequent upper urinary tract infections, and low ﬂ
Struvite stones are associated with urinary tract infection with
urea-splitting bacteria such as
species. Treatment varies
based upon the location and size of the stones and includes
analgesics, shock wave lithotripsy, ureteroscopy, and surgery.
Transitional epithelium, ureter.
lines the urinary tract from the
urinary calyces to the bladder. This type of epithelium can
change shape as it is stretched to accommodate a change in
volume. Cells on the surface layer appear round and dome
shaped when the bladder is in a relaxed state. These cells
attened and the layers of cells are reduced in number
when the epithelium is stretched. The transitional epithelium
lining the urinary tract is also called
; it has tight
junctions and thick cytoplasm (±igs. 12-14B and 12-15A,B).
of the ureter appears as a white space here.