CHAPTER 17
Endocrine System
337
Secretory cells in
zona reticularis
Lipid droplets
Rough
endoplasmic reticulum
Smooth
endoplasmic reticulum
Nucleolus
Mitochondrion with
tubular cristae
A
Figure 17-11A.
Adrenal cortical cells, adrenal cortex.
EM,
3
11,500; inset (
color
) H&E,
3
680
Cells of the
adrenal cortex
have features common to all cells that synthesize and secrete steroid hormones. The three most prominent
components of the cytoplasm are an abundance of
smooth endoplasmic reticulum
(
SER
),
mitochondria
that have peculiar
tubular cris-
tae
, and
lipid droplets. Cholesterol
, the precursor of steroid hormones, is stored as esters in the lipid droplets. Enzymes necessary for
synthesis of steroid hormones are located in the SER and in the inner mitochondrial membrane, so hormone production is a cooperative
function of these two organelles. Although proteins are not secreted by these cells, protein synthesis is required to maintain structure
and function. This is refl ected by the prominent nucleolus and by the patches of RER.
CLINICAL CORRELATION
Figure 17-11B.
Pheochromocytoma.
H&E,
×
96
Pheochromocytomas
are
neoplasms
of the adrenal medulla
characterized by the production of
catecholamines
, such as
epinephrine
and
norepinephrine
, which cause signiF
cant hyper-
tension, often episodic, in affected patients. Most pheochro-
mocytomas are sporadic, but about 10% are associated with
familial syndromes such as
MEN
(
types 2A
and
2B
), and
von
Hippel-Lindau
. Some pheochromocytomas are bilateral, and
although most occur in adults, about 10% occur in children.
Grossly, most of these tumors are well circumscribed and
range in size from a few grams to kilograms. Microscopically,
pheochromocytomas can have a diverse appearance, from
spindle cells to large, bizarre cells. The cells are often arranged
in nests, or cell packets called
zellballen
. Histologic features
alone do not reliably separate benign tumors from malignant
ones; therefore, the demonstration of metastases is necessary to
ascertain malignancy. DeF
nitive treatment is surgical removal
of the tumor.
Pheochromocytoma
with zellballen
Adjacent normal
adrenal cortex
B
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