THE UROGENITAL SYSTEM 
The urogenital apparatus (Apparatus urogenitalis) includes two groups of 
organs, the urinary and the genital. The urinary organs elaborate and remove the 
chief excretory fluid, the urine. The geni- 
tal organs serve for the formation, develop- 
ment, and expulsion of the products of the 
reproductive glands. In the higher verte- 
brates the two apparatus are independent 
except at the terminal part, which consti- 
tutes a urogenital tract, and includes the 
vulva in the female and the greater part of 
the urethra in the male. 
THE URINARY ORGANS 
The urinary organs (Organa uropoiét- 
ica) are the kidneys, ureters, bladder, and 
urethra. The kidneys are the glands which 
secrete the urie; they are red-brown in 
color, and are situated against the dorsal 
wall of the abdomen, being in most ani- 
mals almost symmetrically placed on either 
side of the spine. The ureters are tubes 
which convey the urine to the urinary 
bladder. The latter is an ovoid or piri- 
form sac, which is situated on the pelvie 
floor when empty or nearly so; it is a reser- 
voir for the urine. The urine accumulates 
in the bladder and is then expelled through 
the urethra. 
Fic. 494.—GreNerRAL Dorsat View oF URINARY 
ORGANS OF Horse. 
1, Right kidney; 1’, left kidney; 2, 2, ad- 
renal bodies; 3, 3’, ureters; 4, urinary bladder; 4’, THE URINARY ORGANS OF THE 
anterior end of bladder with cicatricial remnant of 
urachus; 4”, urethra; 5, aorta; 6, 6, renal arteries; HORSE 
7, 7, external iliac arteries; 8, 8, internal iliac ar- THE KIDNEYS 
teries; 9, 9, umbilical arteries. (After Leisering’s 
Atlas.) Each kidney presents two surfaces, 
two borders, and two extremities or poles, 
but they differ so much in form and position as to require a separate description 
of each in these respects. 
The right kidney (Ren dexter) in outline resembles the heart on a playing 
card, or an equilateral triangle with the angles rounded off. It lies ventral to the 
upper parts of the last two or three ribs and the first lumbar transverse process. 
The dorsal surface (Facies dorsalis) is strongly convex; it is related chiefly to the 
diaphragm, but also to a small extent posteriorly to the iliac fascia and psoas 
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