CHAPTER 12
Urinary System
227
CLINICAL CORRELATION
Figure 12-4C.
Glomerular Disorders: Diabetic Nephropathy.
H&E,
3
216
Diabetic nephropathy
, a complication of both type 1 and type
2 diabetes mellitus, may result in chronic renal failure and is
the leading cause of end-stage renal disease in the United States
and other Western countries. Major histologic changes in the
glomeruli in diabetic nephropathy include
thickening of the
glomerular basement membrane
,
diffuse glomerulosclerosis
,
and
nodular glomerulosclerosis
, also called
Kimmelstiel-Wilson
disease
. As the disease progresses, edema (swelling), hyperten-
sion, foamy urine, fatigue, headache, and nausea and vomiting
may occur. Tight control of blood glucose levels tends to delay
the onset of development. Treatment includes dialysis and renal
transplantation. Shown here is a renal glomerulus with nodular
glomerulosclerosis, or Kimmelstiel-Wilson disease.
Kimmelstiel-
Wilson nodules
C
Figure 12-4A.
Renal cortex and medulla, kidney.
H&E,
3
11
This section shows the
renal cortex
and the
medulla
. The
dashed white line
indicates the junction between the cortex and the medulla. The difference
in appearance between the cortex and the medulla is due to the arrange-
ment of the
uriniferous tubules
(
nephrons
and
collecting ducts
). The
renal
cortex
is stained darker than the renal medulla. There are numerous renal
corpuscles and various convoluted tubules in the cortex region. Both the
cortex and the medulla have a rich blood supply. The arcuate vessels (arter-
ies and veins) are visible at the border of the
corticomedullary junction
.
The
interlobular vessels
(arteries and veins) arise from
arcuate vessels
and
course upward (arteries) or downward (veins) in the renal cortex. The
renal
medulla
is composed of 10 to 18 renal pyramids. Each pyramid contains
numerous medullary tubules (
loops of Henle
,
collecting ducts
, and
papil-
lary ducts
). Each papillary duct opens at the surface of the renal papilla
(called the
area cribrosa
) where it empties urine into the minor calyx. The
renal medulla can be divided into inner and outer zones based on differ-
ences in the types of tubules residing in the two regions (Fig. 12-11A–C).
Cortex
Cortex
Cortex
Interlobular
Interlobular
vessel
vessel
Interlobular
vessel
Interlobular
Interlobular
vessel
vessel
Interlobular
vessel
Medulla
Medulla
Medulla
Arcuate
Arcuate
vessel
vessel
Arcuate
vessel
Arcuate
Arcuate
vessel
vessel
Arcuate
vessel
A
Renal
Renal
corpuscles
corpuscles
Renal
corpuscles
Medullary ray
Medullary ray
Medullary ray
Medullary
Medullary
ray
ray
Medullary
ray
Arcuate
Arcuate
vessel
vessel
Arcuate
vessel
Arcuate vessel
Arcuate vessel
Arcuate vessel
B
Figure 12-4B.
Renal cortex, kidney.
H&E,
3
32
The
renal cortex
is composed of the
renal corpuscles
, the
proximal
convoluted tubules
, the
distal convoluted tubules
, and the
cortical
collecting tubules
. The renal corpuscles look like small balls interspersed
among a tangle of tubules (
cortical labyrinth
) in the cortex region. The cor-
tical labyrinth (with its corpuscles) is subdivided into columns by groups
of parallel tubules called
medullary rays
. The medullary rays belong to
the renal medulla proper; however, they extend into the cortex region.
The renal cortex contains various convoluted tubules and is supplied by
interlobular arteries
, which give rise to afferent arteries. The afferent arte-
rioles supply the glomeruli of renal corpuscles; blood exits the glomeruli
through
efferent arterioles
. The cortical tubules are supplied by a peritubu-
lar capillary network, which arises from efferent arterioles that exit renal
corpuscles located in the outer cortex. The renal medulla is supplied by the
vasa recta
, which arise from efferent arteries that exit renal corpuscles in
the inner (juxtamedullary) cortex. The vasa recta follow the loop of Henle
downward into the medulla and loop back toward the cortex. Both the
peritubular capillaries
and
vasa recta
converge into the
interlobular vein
and then drain into the
arcuate vein
at the corticomedullary junction.
Kidneys
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