42
UNIT 2
Basic Tissues
CLINICAL CORRELATION
Figure 3-14C.
Barrett Syndrome (Barrett Esophagus).
Barrett syndrome
(
Barrett esophagus
) is a complication
of chronic gastroesophageal refl
ux disease marked by
metaplasia of the stratiF
ed squamous epithelium of the
distal esophagus into a simple columnar epithelium as
a response to prolonged refl
ux-induced injury. Patients
with Barrett syndrome have a high risk of developing
adenocarcinoma
(cancer of the esophagus). This illustra-
tion shows the
metaplastic columnar cells
and
goblet cells
that have replaced the normal squamous epithelium and
the infl
ammatory cells (mainly
lymphocytes
and
plasma
cells
) inF
ltrating the connective tissue.
D. Cui
Metaplastic columnar cell
Goblet cell
Inflammatory cells
C
D. Cui
Basal cuboidal cell
Basement membrane
Squamous cell
Connective tissue
B
Figure 3-14B.
A representation of nonkeratinized
strati±
ed squamous epithelium.
This type of epithelium is formed by multiple
layers
of cells. The top surface layers are composed of
at-
tened
and
nucleated
live cells, which do not form
keratin. Other general features of
nonkeratinized
strati±
ed squamous epithelium
are similar to kera-
tinized squamous epithelium: The basal layer has
cuboidal
or low column-shaped cells in contact with
a
basement membrane
, intermediate layer cells are
polyhedral in shape, and nuclei become progres-
sively fl
atter as the cells move toward the surface.
Connective
Connective
tissue
tissue
Epithelium
E
p
i
t
h
e
l
i
u
m
Nucleated
Nucleated
squamous
squamous
cells
cells
Stratified
Stratified
squamous
squamous
epithelium
epithelium
(non-keratinized)
(non-keratinized)
Connectiv
tiv
e tis
tis
sue
Epithelium
Epithelium
Stratified
squamous
epithelium
(nonkeratinized)
Connective
tissue
Connective tissue
Nucleated
squamous
cells
Epithelium
Epithelium
A
Figure 3-14A.
Strati±
ed squamous epithelium,
esophagus.
H&E,
3
78; inset
3
175
Strati±
ed squamous epithelium
(
nonkeratinized
) is
usually wet on its surface and is found lining the
mouth, oral pharynx, esophagus, true vocal cords,
and vagina. Nonkeratinized stratiF ed squamous
epithelium is similar to keratinized squamous
epithelium, but the fl
attened surface cells retain
their nuclei, and there is no keratinization of these
cells.
Strati± ed Squamous Epithelium (Nonkeratinized)
In some patients with long histories of
gastroe-
sophageal refl ux
and
heartburn
, the stratiF ed
squamous epithelium in the esophageal-stomach
junction may be replaced by metaplastic colum-
nar epithelium (see ±ig. 3-14C). The
dashed lines
illustrate the depth of the
epithelial layer
.
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