CHAPTER 16
Digestive Glands and Associated Organs
309
Salivary Glands
Figure 16-3A.
General structure of the major salivary glands.
The
parotid
,
submandibular
, and
sublingual glands
are structurally very similar to one another, although they produce various
secretions. Each unit of the salivary glands can be divided into a
secretory portion
and a
duct system
. The
secretory portion
contains
serous cells
,
mucous cells
, or a
mixture
of both. These secretory cells are arranged into acini resembling grapes on a stem (interca-
lated duct). Several serous cells form a cap, called a
serous demilune
, on the outer aspect of mucous cells; this arrangement can be
found in the mixed glands. A capsule (dense connective tissue layer) surrounds an entire gland. Connective tissue septa penetrate the
gland and subdivide it into
lobes
and
lobules
. The
duct system
includes
intralobular ducts
(located within the lobules),
interlobular
ducts
(outside or between the lobules),
lobar ducts
, and a
main duct
. The
intralobular ducts
include
intercalated ducts
and
striated
ducts
. The
main duct
empties the secretory products (saliva) into the oral cavity.
Figure 16-3B.
Parotid gland.
H&E,
3
130 skin, palm.
The
parotid glands
are paired glands and are the largest of the major
salivary glands. They are located anterior to and below the lower
half of the ear, and superior, posterior, and deep to the ramus of
the mandible. The
main duct
of each parotid gland passes through
the cheek and opens into the oral cavity near the second upper
molar tooth (see Fig. 16-1). The parotid glands are composed of
serous acini
and
ducts
. They are classi±
ed as
compound (branched)
acinar glands
based on their duct shape and secretory units (see Fig.
3-27A). This photomicrograph shows
striated ducts (intralobular
ducts)
located in the lobules. The striated ducts are lined by taller
cuboidal (or columnar) cells with centrally located nuclei (see Fig.
16-7A). Connective tissue septa divide the gland into small lobules,
and there are some adipose cells distributed in among the serous
acini. Each acinus is formed by several serous cells with basally
positioned dark nuclei (Fig. 16-4A).
Salivary Gland Duct System
D. Cui
Lobar duct
(a few branches)
Interlobular duct
(multiple branches)
Intralobular duct
(multiple branches)
Secretory portion
Duct system
Serous
cells
Serous
acinus
Serous
demilune
Intercalated
ducts
Lumen of the
Intercalated ducts
Striated
ducts
Mucous
cells
A
Striated
Striated
ducts
ducts
Striated
ducts
Striated
Striated
duct
duct
Striated
duct
Septa
Septa
Septa
Adipose
Adipose
cells
cells
Adipose
cells
Serous acini
Serous acini
Serous acini
B
D. Cui
(Serous, mucous, or mixed cells)
(Simple low cuboidal epithelium)
Small intralobular duct
(Intercalated duct)
Interlobular duct
Main duct
(Stratified columnar epithelium)
(striated duct)
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