264
UNIT 3
Organ Systems
Moat (groove)
Moat (groove)
Moat (groove)
Lateral wall
Lateral wall
(taste buds)
(taste buds)
Lateral wall
(taste buds)
Duct of the
Duct of the
Von Ebner glands
Von Ebner glands
Duct of the
Von Ebner glands
Von Ebner
Von Ebner
glands
glands
Von Ebner
glands
Taste buds
Circumvallate
papilla
A
Figure 14-6A.
Circumvallate papillae
,
tongue
. H&E,
3
34 inset
3
181
The
circumvallate papillae
are also called
vallate papillae
.
They are arranged in a single row, which contains about
10 to 14 papillae that are located immediately anterior to the
sulcus terminalis
(Fig. 14-5A). Each circumvallate papilla is
cylindrical in shape and is surrounded by a groove called a
moat
. The ducts of the
glands of von Ebner
(minor serous
salivary glands) open and drain serous products into the
groove; this helps to clear the food debris in the groove and
helps in detection of taste. Most minor salivary glands in the
oral cavity are mucous or mixed glands; von Ebner glands
are the only ones that are pure serous glands. The taste buds
of the circumvallate papillae are located on the lateral walls
of the groove. These taste buds are mainly
bitter receptors
and are innervated by the glossopharyngeal nerve (CN IX).
Foliate
papilla
Taste receptor cell
Taste receptor cell
Taste receptor cell
Taste pore
Taste pore
Taste pore
Basal cell
Basal cell
Basal cell
Taste buds
Taste buds
Taste buds
B
Figure 14-6B.
Foliate papillae and taste buds
,
tongue
.
H&E,
3
68 inset
3
222
The
foliate papillae
are located on the posterior lateral
surface of the tongue. This type of papilla is not well devel-
oped in humans but is frequently found in animals; illus-
trated here from rabbit tissue.
In general,
taste buds
are ovular structures embedded
in nonkeratinized strati± ed squamous epithelium of the
papillae of the tongue. They also can be found in the pal-
ate of the oral cavity and in the mucosa of the oropharynx
and epiglottis. Each taste bud is composed of 40 to 60 elon-
gated
taste receptor cells
with microvilli at the apical region,
which extend into the
taste pore
. The basal end of the taste
bud contacts an afferent nerve ± ber. The taste pore is a small
opening that allows taste molecules to contact taste recep-
tor cells. The taste receptor cells have a life span of 1 to
2 weeks, and new taste cells arise from basal cells at the basal
lateral region of the taste bud. The
inset
shows taste buds.
Name
Epithelial Covering
Taste Buds
Location
Main Function
Filiform papillae
Keratinized strati± ed
squamous epithelium
No taste buds
Anterior 2/3 of tongue
Helps in chewing and
mixing food
Fungiform papillae
Nonkeratinized strati± ed
squamous epithelium
Taste buds located at
the apical surface of
papillae
Tip and two sides of
tongue
Chemoreceptor
detecting taste
Circumvallate
papillae
Nonkeratinized strati± ed
squamous epithelium
Taste buds located at
the lateral surface of
papillae
In a V-shaped row just
anterior to the sulcus
terminalis
Chemoreceptor
detecting taste
Foliate papillae
Nonkeratinized strati± ed
squamous epithelium
Taste buds located at
the lateral surface of
papillae
Posterior lateral
surface of the tongue
Chemoreceptor
detecting taste
TABLE 14-2
Comparison of Lingual Papillae
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