CHAPTER 15
Digestive Tract
295
Secretory
Secretory
granules
granules
Secretory
granules
Gland of
Gland of
Lieberkühn
Lieberkühn
Gland of
Lieberkühn
Nuclei of the
Nuclei of the
paneth cells
paneth cells
Nuclei of the
paneth cells
A
Figure 15-13A.
Paneth cells, small intestine.
H&E,
3
702; inset
3
1,488
Paneth cells
have basally positioned nuclei and contain
acidophilic-secretory granules
in the apical region of the
cytoplasm. These granules appear bright red in H&E stains.
Paneth cells are located at the base of the
glands
(
crypts
)
of
Lieberkühn
. Their secretory granules contain
lysozymes
,
tumor necrosis factor-
a
, and
defensins
(
cryptidins
). These
are antibacterial enzymes that help to regulate the normal
bacterial fl
ora of the intestine. Paneth cells are
protein-
secretory cells
and have well-developed
rough endoplasmic
reticulum
(
RER
) and
Golgi complexes
. Like other epithelial
cells, the Paneth cells are derived from stem cells located at
the base of the intestinal glands of
Lieberkühn. A gland of
Lieberkühn is indicated by the
dashed line
at left. Its lumen
is F
lled with secretory
material and is not easy to see.
Figure 15-13B.
Enteroendocrine cells, small intestine.
EM,
3
10,611; (color)
3
1,028
There are many types of
enteroendocrine cells
, which are also called
diffuse neuroendocrine cells
, in the digestive tract. They are recog-
nized as
hormone-releasing cells
, and the various types of enteroendocrine cells are similar in appearance. They are often found at the
base of glands of Lieberkühn and have many mitochondria, abundant RER, and well-developed Golgi complexes (see ±ig. 15-11A).
Their secretory granules are located at the basal cytoplasm. Each type of enteroendocrine cell releases one particular hormone.
Paneth cell
Paneth cell
Paneth cell
Enteroendocrine cell
Enteroendocrine cell
Enteroendocrine cell
Nucleus of enteroendocrine cell
Rough endoplasmic reticulum
Secretory granules
Basal lamina
Endothelial cell of capillary
Mitochondria
B
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