234
UNIT 3
Organ Systems
Figure 12-11A.
Medullary tubules, outer zone of the medulla.
H&E,
3
296; inset
3
435
The
renal medulla
is composed of the
loop of Henle
, the
collecting
ducts
, and the
papillary ducts
(
ducts of Bellini
). It can be divided
into an outer zone and an inner zone. The
thin segment tubules
and
distal straight tubules
of the loop of Henle and
collecting
ducts
of the outer zone are shown here. The inner zone contains
only thin segments and collecting ducts, along with the
vasa recta
.
Blood vessels (vasa recta) are found throughout the medulla.
Vasa recta
Vasa recta
(blood vessels)
(blood vessels)
Vasa recta
(blood vessels)
Distal straight
Distal straight
tubule
tubule
Distal straight
tubule
Thin
Thin
segment
segment
Thin
segment
Thin
Thin
segment
segment
Thin
segment
Vasa recta
Vasa recta
Vasa recta
Thin
Thin
segment
segment
Thin
segment
Collecting
Collecting
duct
duct
Collecting
duct
A
D. Cui
&T. Yang
Loop of Henle
Papillary duct
Collecting
duct
Collecting
tubule
Cortex
Outer
medulla
(Fig. 12-11A)
(Fig. 12-11B)
Inner
medulla
B
Collecting
Collecting
duct
duct
Collecting
duct
Vasa
Vasa
recta
recta
Vasa
recta
Thin
Thin
segment
segment
Thin
segment
Vasa
Vasa
recta
recta
Vasa
recta
Collecting
Collecting
duct
duct
Collecting
duct
Thin
Thin
segment
segment
Thin
segment
C
CLINICAL CORRELATION
Figure 12-11D.
Renal Cell Carcinoma (Clear Cell Type).
H&E,
3
216
Renal cell carcinoma
, which arises from the
renal tubular
epithelium
, is the most common renal cancer in adults. Risk
factors for development of renal cell carcinoma include
smok-
ing
, exposure to
toxic substances
,
chronic renal failure
, and
acquired cystic disease
of the kidney as well as
genetic predis-
position
in various familial syndromes. Renal carcinoma pres-
ents clinically with hematuria, abdominal mass, or fl
ank pain.
Renal cell carcinoma tends to metastasize early, especially to the
lungs and bones. On gross examination, renal cell carcinoma is
well circumscribed, lobulated, and yellow, with areas of hemor-
rhage and necrosis. The most common renal cell carcinoma is
the
clear cell type
, the cells of which may be arranged in cords,
nests, or tubules. The cells are large and polygonal with clear or
granular cytoplasm. Other types of renal cell carcinoma include
papillary carcinoma, chromophobe carcinoma, and collecting
duct carcinoma. Treatment is primarily surgical removal, with
lesser roles for immunotherapy and chemotherapy.
Clear cells
(tumor cells)
D
Figure 12-11B.
Orientation of the kidney tubules in the cortex
and medulla.
This illustration shows the orientation of the kidney
tubules
in
the
cortex
and
medulla
. The outer zone and inner zone of the
medulla indicate the levels of Figures 12-11A and 12-11B.
Figure 12-11C.
Medullary tubules, inner zone of the medulla.
H&E,
3
296; inset
3
726
This ±
gure shows the inner zone of the medulla. The
collecting
ducts
gradually increase in size. The
thin segment tubules
and the
vasa recta
(blood vessels) are seen here.
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