44
UNIT 2
Basic Tissues
Stratified
Stratified
columnar
columnar
epithelium
epithelium
Stratified
columnar
epithelium
Stratified
columnar
cells
Connective
Connective
tissue
tissue
Connective
tissue
A
Figure 3-16A.
Stratif
ed columnar epithelium,
eyelid.
H&E,
3
155; inset
3
295
Stratif
ed columnar epithelium
can be found lining
the palpebral conjunctiva of the eyelid. The ante-
rior surface of the eyelid is covered by keratinized
stratiF
ed squamous epithelium (epidermis of thin
skin); the posterior surface of the eyelid, which is
in contact with the surface of the eyeball, is lined by
stratiF
ed columnar epithelium as demonstrated here.
The
basal
cells
are cuboidal in shape, and the
sur±ace
layer
cells
are low columnar in shape (only slightly
taller than wide). The conjunctiva has a smooth sur-
face that is kept moist and lubricated by tears and
a mucinous substance in the normal condition. The
arrowheads
point to
columnar cells
of the surface
layer of the epithelium (
inset
).
Stratif ed Columnar Epithelium
D. Cui
Cuboidal cell
Columnar cell
Basement membrane
Connective tissue
B
Figure 3-16B.
A representation o± the stratif ed
columnar epithelium lining the conjunctiva o± the eye.
Stratif
ed columnar epithelium
usually has two or
three layers; the top layer is made up of
colum-
nar cells,
and the basal layer normally consists of
cuboidal cells
. StratiF
ed columnar epithelium is not
a common type of epithelium and is found in only a
few places in the body, for example, the larger ducts
of some exocrine glands and the lining of the palpe-
bral conjunctiva of the eyelid.
CLINICAL CORRELATION
Figure 3-16C.
Trachoma.
Trachoma
is a chronic contagious conjunctivitis (eye
disease) characterized by infl
ammatory granulation on
the conjunctival epithelium surface caused by the bac-
teria
Chlamydia trachomatis
. This form of
“pink eye”
often presents with bilateral
keratoconjunctivitis
with
symptoms of tearing, discharge, photophobia, pain, and
swelling of the eyelids. It can cause eyelid deformities
and turned-in eyelashes that scrape against the cornea. If
left untreated, ulceration and infection of the cornea may
occur. Trachoma can even cause loss of vision if scarring
occurs on the central part of the cornea.
Lymphocytes
and
macrophages
invade underlying connective tissue as
part of the infl
ammatory response. The epithelial
hyper-
plasia
and
inclusion bodies
in the epithelial cells are illus-
trated here.
D. Cui &L Lynch
Inclusion body
Granulated surface
Macrophage
Lymphocyte
C
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