CHAPTER 16
Digestive Glands and Associated Organs
311
Septum
Septum
Septum
Serous
Serous
demilunes
demilunes
Serous
demilunes
Septum
Septum
Septum
Serous
Serous
acini
acini
Serous
acini
Serous
Serous
demilune
demilune
Serous
demilune
Striated
Striated
duct
duct
Striated
duct
Mucous
Mucous
cells
cells
Mucous
cells
A
Figure 16-5A.
Submandibular glands.
H&E,
3
136; inset
3
408
Submandibular glands
are also paired glands. They are smaller than
the parotid glands, but larger than the sublingual glands. Each sub-
mandibular gland is divided into
superf cial (large)
and
deep (small)
lobes
and is located under the fl oor of the oral
cavity adjacent to
the mandible (see Fig. 16-1). The
main duct
of the submandibular
gland drains
saliva
into the oral cavity at the
sublingual caruncles
on
both sides of the frenulum linguae. The submandibular glands are
mixed glands that contain predominantly
serous cells
but also some
mucous cells
. They are classi± ed as
compound (branched) tubulo-
acinar glands
(see Fig. 16-3A; see also Chapter 3, “Epithelium and
Glands,” Fig. 3-28A). Serous cells are arranged into many acini, and
mucous cells are arranged as acini or tubular structures, which may
have caps of serous cells
(serous demilunes)
. Submandibular glands
are innervated by
parasympathetic nerve f bers
from branches of
the
±acial nerve (CN VII)
.
Myoepithelial
cell
Serous acinar
cell
Secretory
granules
Nucleus of the
Nucleus of the
acinar cell
acinar cell
Nucleus of the
acinar cell
Lumen
Lumen
Lumen
RER
RER
RER
B
Figure 16-5B.
Serous acinus, submandibular gland.
EM,
3
3,937; inset (
color
), H&E,
3
1,079
Several
serous acinar cells
arranged in an
acinus
and sharing a common lumen are shown. The serous lumens are smaller than those
of a mucous acinus (see Fig. 16-6A). Each secretory cell has a relatively large nucleus and numerous
rough endoplasmic reticulum
(RER)
cisterns in the basal portion of the cytoplasm. These features indicate their active protein synthesis.
Secretory granules
are
usually located on the apical region of the cells (
color inset
). Secretory granules are not seen in this electron micrograph because they
have already been discharged from these particular cells. The
inset
shows an acinus with secretory cells having round nuclei located
basally and many secretory granules in the apical portions of the secretory cells. A
myoepithelial cell
with a fl
at nucleus is present
here, located beneath the serous cell. It is a contractile cell and contains
smooth muscle myosin
. The myoepithelial cells contract and
move the secretory products toward the intercalated duct.
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