Clinical Anatomy of the European Hamster 
status of the animals the kidneys are embedded in 
perirenal fat (capsula adiposa) (Fig. 5-48). Espe- 
cially in autumn, the hamsters accumulate much 
fat around the kidneys in preparation for hiberna- 
tion. 
The outer covering of the kidneys is a thin but dense connective tis- 
sue capsule (capsula fibrosa) from which thin filaments proceed into 
the kidnev proper. The entire parenchyma consists of densely packed 
tubules which are embedded in loose connective tissue through which 
the renal vessels, lymphatics and nerves run. The renal cortex {cortex 
renis) is comprised of the renal corpuscles (corpuscula rents) (Figs. 5- 
52, 5-53), and the proximal convoluted tubules (tubuli reriales con- 
lorti) the terminal parts of which become either straight (tubuli renales 
recti) or slightly spiralled (spiral tubules). These spiral tubules run 
toward the medulla (medulla renis) to become the descending limb of 
Henle's loop, connected by a U-turn to the ascending limb. The renal 
tubules are lined by a single layer of epithelial cells, outside of which is 
a basement membrane. The height of the epithelial cells varies in the 
different parts of the tubules. The renal medulla consists of radiating 
straight-running tubules which discharge at the papillary surlaces mto 
the calyces (calices renalei) (Fig. 5-54). The pelvis of the kidney (pel- 
vis renalis) is lined with simple polygonal epithelium without glands 
(Fig. 5-55.) 
5.6.3.2.2 Ureter 
The ureter transfers the continually-produced 
urine from the renal pelvis to the urinary bladder 
(vesica urinaria), where the urine is stored. The 
ureters leave the renal pelves caudomedially and 
proceed in a caudal direction; they are protected by 
a rich retroperitoneal fatty tissue. They continue 
parallel to the aorta and caudal vena cava (Fig. 5- 
47) and discharge on each side into the dorsal wall 
of the urinary bladder. The course of the ureters 
differs somewhat between the sexes. In males the 
ureter runs dorsal to the vesicular gland (gl. vesicu- 
laris) and the ductus deferens, crossing the latter 
and emptying into the bladder. The female ureters 
run dorsal to the uterine horns {cornua uteri) and 
lateral to the cervix {cervix uteri). 
The ureters have three layers: fibrous, muscular and mucous (luni- 
cae adventitia, muscularis, mucosa). The fibrous layer is continuous 
at one end with the fibrous capsule of the kidney in the floor of the renal 
pelvis while, at the other end, it merges with the wall of the urinary 
bladder. The muscular coat consists of an outer circular part and an 
inner longitudinal part. TTie mucous layer is smooth with longitudinal 
folds. It contains many elastic fibers and is covered with a transitional 
epithelium, four or five cells thick. 
5.6.3.2.3 Urinary Bladder 
Depending upon the degree of distension, the 
urinary bladder (vesica urinaria) is about the size 
of a cherry and projects, even when only slightly 
distended, over the pubic crest into the ventral pubic 
region (regio pubica) (Fig. 5-48). The walls of the 
urinary bladder are so thin that one can view the 
contents of the bladder. In male hamsters, the blad- 
der is bordered lateroventrally by the abdominal 
wall and cranially by the caecum or distended loops 
of the small intestine. Dorsal to the bladder lie the 
vesicular glands and the well-developed ampulla of 
the ductus deferens (Fig. 5-59). The male urethra 
(urethra masculina) extends along the ventral side 
of the penis. The external orifice of the urethra (os- 
tium urethrae externum) is not at the end of the 
penis, which has two points at its tip, but rather on 
the ventral surface of the circular mucosal fold. In 
female hamsters, the urinary bladder pushes ven- 
trally against the abdominal wall, cranially against 
the caecum and jejunal loops, and dorsally against 
the uterine horns and cervix. The middle ligament 
of the bladder (lig. vesicae medianum) is well de- 
fined, and two lateral true ligaments (ligg- vesicae 
laterales) are erected as small serous folds towards 
the lateral abdominal walls. The urethra of the fe- 
male (urethra feminina) discharges separately from 
the vagina and the anus. Thus, while the female 
urethra is purely a urinary duct, the male urethra 
serves two functions, urinary and reproductive. 
The bladder has a wall similar to that of the 
ureters. The abdominal surface is covered by 
peritoneum. 
The muscular stratum (m. pubovesicalis and m. rectourethralis), 
consists of three layers of smooth muscle — an external and an internal 
layer of longitudinal fibers and a middle layer of circular fibers The 
mucous membrane is whitish-pink in color. It is continuous above with 
the mucous membrane of the ureters and below with that of the ureth- 
ra. The epithelium is of the transitional type, 3 or 4 cells thick (Fig 
5-56). The loose texture of the submucosa allows the mucosa to be 
thrown into folds or rugae when the bladder is in an empty state. 
5.6.4 Adrenal Gland 
The adrenal glands (gll. suprarenales) belong to 
the endocrine system. The cells of their cortex pro- 
duce corticosteroids, whereas those of the medulla 
synthesize noradrenalin and adrenalin. 
The adrenals are located at the level of the last 
thoracic vertebra or the first lumbar vertebra, cra- 
niomedial to the kidneys, 1 to 3 mm lateral to the 
abdominal aorta and caudal vena cava (Fig. 5-50). 
The right adrenal gland, like the right kidney, is 
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