histology of colecting tubule and duct
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Figure 1922. Photomicrograph of renal medulla with 2 collecting ducts consisting of cuboidal cells resting on a basement membrane. In this hypertonic region
of the kidney, because of the action of the hypophyseal antidiuretic hormone, water is reabsorbed, controlling the water balance of the body
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Figure 1923. Electron
micrograph of a collectingtubule wall. M,
mitochondria; NU,
nucleolus. x15,000.
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Ureter
The ureters are muscular tubes, 2530 cm long, that connect the kidneys to the urinary bladder. The ureter are retroperitoneal; their superior
halves are in the abdomen (see Chapter 2) and their inferior halves lie in the pelvis. As the ureter cross the bifurcation of the common iliac artery or
the beginning of the external iliac artery (Fig. 3.14A) they pass over the pelvic brim, thus leaving the abdomen and entering the lesser pelvis. Thepelvic parts of the ureter run on the lateral walls of the pelvis, parallel to the anterior margin of the greater sciatic notch, between the parietal
pelvic peritoneum and the internal iliac arteries. Opposite the ischial spine, they curve anteromedially, superior to the levator ani, to enter the
urinary bladder. The inferior ends of the ureters are surrounded by the vesical venous plexus (Fig. 3.13B & C). The ureters pass obliquely through
the muscular wall of the urinary bladder in an inferomedial direction, entering the outer surface of the bladder approximately 5 cm apart, but their
internal openings into the lumen of the empty bladder are separated by only half that distance. This oblique passage through the bladder wall
forms a one-way flap valve, the internal pressure of the filling bladder causing the intramural passage to collapse. In addition, contractions
of the bladder musculature act as a sphincter preventing the reflux of urine into the ureters when the bladder contracts, increasing internal
pressure during micturition. Urine is transported down the ureters by means of peristaltic contractions, a few drops being transported at intervals
of 1220 sec.
In males, the only structure that passes between the ureter and the peritoneum is the ductus deferens (Fig. 3.14B); it crosses the ureter within the
ureteric fold of peritoneum. The ureter lies posterolateral to the ductus deferens and enters the posterosuperior angle of the bladder, just superior
to the seminal gland.
In females, the ureter passes medial to the origin of the uterine artery and continues to the level of the ischial spine, where it is crossed superiorly
by the uterine artery (see clinical correlation [blue] boxes Iatrogenic Injury of the Ureters during Ligation of Uterine Artery andIatrogenic Injury of the Ureters during Ligation of Ovarian Artery, in this chapter). It then passes close to the lateral part of the fornix
of the vagina and enters the posterosuperior angle of the bladder.
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