Wheater, 1993
This shows you a section
of a blood vessel
illustrating a simple
squamous epithelium (E).
Note that the epithelium
is so thin that the only
thing you can really see
of these cells are their
flattened nuclei, which
bulge into the lumen of
the blood vessel. (The
pinkish cells are red
blood cells in the lumen
of the blood vessel)
EPITHELIUM
Following are a series of images and
descriptions to assist you in learning the
characteristics of epithelia and its various
subtypes.
Wheater, 1993
This shows a very thin,
simple squamous
epithelium (mesothelium)
that has been spread
onto a slide and stained
so that you are looking
down onto the tissue.
Note that the cells are
tightly packed together
with little intracellular
material (the dark lines
indicate the cell
boundaries). The nuclei
are indicated by “N”.
GC
This shows a section of
the small intestine
illustrating the simple
columnar epithelium with
microvilli (arrow) on the
apical surface. Notice
that the epithelium is a
single layer of cells and
that these cells are taller
than they are wide. Note
also the Goblet cells
within the epithelium
(GC).
C
SC
This shows the simple
columnar ciliated
epithelium of the
oviduct. Note that
many of the cells
contain cilia (C)
extending from their
apical surfaces. Note
also the secretory
cells (SC) that are
nonciliated.
This shows the
pseudostratified columnar
epithelium of the
epididymis. This
epithelium appears to be
stratified but in fact all of
the cells make contact
with the basement
membrane. Note that the
epithelial cells contain
stereocilia extending from
their apical surfaces
(arrows).
This shows a section of the
dermal portion of the
integument (skin). Seen in the
center of the field are a
number of cross-sections of a
sweat gland. Notice that some
of the tube-like structures have
simple cuboidal epithelium
(black arrow). This is the
secretory portion of the sweat
gland. Other parts of the gland
have stratified cuboidal
epithelium (green arrow). This
is the duct of the sweat gland.
Ep
Connective Tissue
This shows a section of
thin skin illustrating a
stratified squamous
epithelium that is
keratinized (Ep). Notice
that the outer portion of
the epithelium consists of
extremely flattened
(almost scaly in
appearance), dead cells
(arrow). No noticeable
organelles remain in
these cells, hence this is
termed a keratinized
epithelium.
Stratified Squamous
Simple Columnar
Connective Tissue
This shows the
epithelium at the
junction of the
endocervix and
ectocervix. Note the
stratified squamous
epithelium
(nonkeratinized) on
the left and the simple
columnar epithelium
on the right.
GC
Connective Tissue
This shows a section
of the nasal cavity
illustrating the
pseudostratified
columnar epithelium
with cilia. Goblet cells
(GC) can also be
distinguished here as
the pale-staining
epithelial cells.
Connective Tissue
This shows the
pseudostratified
columnar epithelium
of the trachea. Cilia
extending from the
apical surface of the
epithelial cells can be
seen much better
than in the previous
micrograph.
Stratified Squamous
Pseudostratified Columnar
This shows a section
of the larynx
illustrating
pseudostratified
columnar epithelium
on the right and
stratified squamous
epithelium on the left.
The cilia are difficult
to discern at this
magnification.
Connective Tissue
This shows a section of
the epithelium lining the
cervix containing stratified
columnar epithelium.
Note that it is the shape
of the cells adjacent to
the free surface by which
the epithelium is named
(i.e. the surface cells here
are columnar in shape)
Connective Tissue
This illustrates the
transitional epithelium
lining the urinary bladder.
Note that the epithelium
is stratified and that the
surface cells are of
diverse shapes. This
epithelium is distensible
(can be stretched). The
stretched cells tend to
flatten while those not
stretched tend to be
dome-shaped and bulge
into the lumen (arrow).
Smooth
Muscle
Connective Tissue
This shows a section of
the colon illustrating
simple tubular glands
(arrows) called the Crypts
of Lieberkuhn (or
intestinal crypts). Note
that these appear in
section as relatively
simple invaginations of
the surface epithelium.
GC
Villus
BG
This shows a section of the
duodenum illustrating fingerlike folds termed villi that are
lined with simple columnar
epithelium. The epithelium
contains Goblet Cells (GC; the
almost empty-appearing cells
within the epithelium). The
epithelium also contains
Crypts of Lieberkuhn as seen
in the previous slide. Below
the Crypts of Lieberkuhn are
other glands that extend into
the connective tissue termed
Brunner’s Glands (BG). These
are compound tubular glands.
D
This shows a section of the
submandibular gland
illustrating the compound
acinar type of gland. Note the
presence of mucous (black
arrow) and serous (green
arrow) cells. The mucous cells
typically appear empty with
routine tissue processing
because the secretory
contents are lost during the
preparation of the tissue. Also
notice the ducts lined with
simple columnar type of
epithelium (D).
D
This shows a section
of a mammary gland
illustrating a
compound acinar
(alveolar) type of
gland. Note the
abundant crosssections of glandular
material and the large
duct (D).
SC
This illustrates the
secretory cells of the
mammary gland at
higher magnification.
Note that the
secretory portion of
the gland is lined by
simple cuboidal
epithelium (SC).
M
C
This shows a scanning
electron micrograph of
the epithelium of the
oviduct (you are
essentially looking onto
the surface of the
epithelium from within the
oviduct). Some of the
epithelial cells have cilia
(C) while others have
microvilli (M).
M
C
This shows a
transmission electron
micrograph of the oviduct
epithelium illustrating
cells that have cilia (C)
and others that have
microvilli (M) on their
surface. Note the
difference in size and
composition of these
structures.
*
This shows a higher
magnification
transmission electron
micrograph of cilia.
Note in the crosssections of cilia (*) the
arrangement of the
microtubules within
the cilium.
Cilium
Microtubules
This shows a
transmission electron
micrograph of cilia in
cross-section. Note
the characteristic
arrangement of
microtubules in the
cilia (i.e. two central
microtubules
surrounded by 9 other
pairs).
Zonula occludens
Zonula adeherens
Macula adherens
BB
This shows a transmission
electron micrograph of the
epithelium of the cervix. Seen
are the apical portions of two
epithelial cells. Note that the
cell to the left has microvilli
and cilia on its surface. Two
basal bodies (BB) are
associated with the cilia in the
cell to the left. Also notice the
junctional complex between
the two cells. What other
structures can you identify
here?
This shows another
transmission electron
micrograph of the
cervix epithelium.
Notice the junctional
complex between the
two epithelial cells.
BL
Glycogen
CT
This transmission
electron micrograph
shows the basal
portion of an
epithelium. Notice
the basal lamina (BL)
separating the
epithelium from the
underlying connective
tissue (CT).