50
UNIT 2
Basic Tissues
Exocrine Glands Classif ed by Morphology
The
exocrine glands
also can be classif
ed into
unicellular
and
multicellular glands
depending upon the
number
oF
cells
that Form
the gland.
Figure 3-20A.
Unicellular gland, small intestine.
H&E,
3
962
Unicellular glands
are composed oF only a
single cell
. The secre-
tory products are released directly onto the surFace oF an epithe-
lium.
Goblet cells
are an example oF this type oF gland. Microvilli
with glycocalyx coating Form a
brush border
(
arrows
). Note that
goblet cells themselves do not have microvilli on their apical
surFaces (see ±ig. 3-20B).
Goblet
Goblet
cell
cell
Goblet
cell
Bru
ru
sh b
b
ord
rd
er
Brush border
Lum
en
Lumen
A
Secretory
granules
(mucous granules)
Rough
endoplasmic
Rough endoplasmic
reticulum (RER)
reticulum (RER)
Rough
endoplasmic
reticulum (RER)
Nucleus
Nucleus
Nucleus
Golgi
Golgi
complex
complex
Golgi
complex
Microvilli
Lumen
B
Figure 3-20B.
Goblet cell, unicellular glands (single-cell gland).
EM,
3
5,100
The
goblet cell
can be considered a
single-cell gland
because it is commonly inserted into an epithelium among nonsecretory cells. In
this example, the goblet cell is surrounded by
enterocytes
, absorptive cells oF the small intestine. Goblet cells are also Found among
ciliated cells in the respiratory epithelium. Typical Features oF goblet cells are illustrated here. The relatively small
heterochromatic
nucleus
is packed into the narrow base oF the cell along with some
RER
. A
Golgi complex
is barely visible adjacent to the apical end
oF the nucleus. Most oF the
cytoplasm
is f lled with
secretory vesicles
.
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