Taste bud/certified fixed orthodontic courses by Indian dental academy

Taste buds
• INDIAN DENTAL
ACADEMY
Leader in
continuing
Dental
Education
www.indiandentalacademy.com

Learning objectives
At the end of seminar learner should be able to describe:
• Development of tongue
• Papillae of tongue
• Nerve supply of tongue
• Structure of taste buds
• Taste pathway
• Taste receptors
• Abnormalities in taste

Introduction
• Tongue is highly muscular & vascular organ of
deglutition, taste and speech.
• It is partly oral and partly pharyngeal in position.
• It has a root , apex, a curved dorsum and inferior
surface.
• Dorsal surface of tongue is thick and covered with
keratinized and non keratizised stratified squamous
epithelium .
• Lingual papillae are present bearing taste buds which
are specialized sense organ for gustation.

Embryology
copula
Lateral lingual
swelling
Tubercular
impar
Foramen
cecum
Hypobranchial
eminence
•Tongue appears in embryo at
approximately 4th
week in utero.
•Anterior 2/3rd
of tongue develops in
utero by fusion of two lateral swelling
and a midline swelling referred to as
tuberculum impar.
• All these structure arises from first
branchial arch.
•Lateral lingual swelling subsequently
merge with and grow over
tuberculum impar.
•Posterior portion of tongue: 2nd
& 3rd
branchial arch.

The point of fusion between tubercular
impar at the anterior 2/3rd
& posterior
portion of tongue corresponds to
epithelial cells.
These epithelial cells subsequently
migrate to form thyroid gland . This
point is marked by foramen cecum.
Foramen cecum & V shaped row of
vallate papillae that extends anteriorly
& laterally separates oral &
pharyngeal portion of tongue.
Posterior part of fourth branchial arch
marks development of epiglottis.
Lateral lingual
swelling
Tubercular
impar
Foramen
cecum
Hypobranchial
eminence
copula

Papillae of tongue
Filiform papillae-
• Slender, conical papillae
covered with keratinized
epithelium and
connective tissue core.
• They cover entire anterior
surface of the tongue.
• Do not carry taste buds.

Fungiform papillae :
• Found mostly at the side
and tip of the tongue.
• Mushroom-shaped
structures have a rich
capillary network.
• Identified as reddish
dots.
• Carries about 1 to 3 taste
buds only on their dorsal
surface.

Circumvallate papillae:
• In front of dividing V- shape teminal sulcus row of
vallate papillae are present.
• 8 – 12 in number.
• Each of them contains upto 100 taste buds.
• They are large and bounded by deep circular furrow .
• Lateral wall of these papillae contains numerous taste
buds.
• Ducts of small serous glands von Ebner’s gland open
into trough of circumvallate papillae.

Circumvallate papillae
Taste bud in lateral wall
of vallate papillae

Foliate papillae
• They are found on
posterior side of the
tongue in front of
palatoglossal arch.
• 4 -10 vertical folds are
present.
• Each papilla contains
upto 100 taste buds
• Taste buds are present in
the lateral wall of the
fold.

Taste buds
• Also called gustatory calculi.
• There are about 10,000 taste buds.
• 80μm high & 40μm thick.
• They are present on epiglottis, soft palate, pharynx and
walls of papillae of tongue.
• Numerous taste buds are found on lateral wall of vallate
papillae , in folds of foliate papillae ,on posterior surface
of epiglottis.
• Some are found on fungiform papillae at the tip and
lateral border of tongue.

Structure of taste bud
•These are small ovoid or
barrel –shaped intraepithelial
organs.
•They extend from basal
lamina to the surface of the
epithelium where it opens by
a taste pore or gustatory
aperture.
•Taste pore lead into a narrow
space lined by supporting
cells.
• The apical ends of taste cells
have microvilli that project
into the taste pore.

• Outer supporting cells are
• arranged like staves of barrel.
• Inner supporting cells are shorter
and spindle shape.
• Between inner supporting cells
• 10-12 neuroepithelial cells or taste
cells are present .
•The basal cells arise from the
epithelial cells surrounding the
taste bud.
• They differentiate into new
taste cells, and the old cells are
continuously replaced with a
time of about 10 days.

•Ultrastructural studies reveal three distinct anatomical
types of taste cells within each taste bud:
• Type I – dark cells
• Type II – light cells
• Type III – intermediate cells. (Murray,1973).
•Each taste bud is innervated by about 50 nerve
fibers, and conversely, each nerve fiber receives
input from an average of five taste buds.

T2R
T1R3
Gustducin
GLAST SNAP25
NCAM

Distribution of primary taste sensation

• Sweet taste sensation
perceived at the tip of
tongue.
• Associated with
fungiform papillae.
• Mediated by chorda
tympani nerve.

• Salty taste sensation
perceived at the lateral
border of tongue.
• Associated with
fungiform papillae.
• Mediated by chorda
tympani nerve.

• Sour taste sensation
perceived by posterio-
lateral part of the tongue.
• Associated with foliate
papillae .
• Mediated by
glossopharyngeal nerve.

• Bitter taste sensation
perceived by posterior
part of the tongue.
• Associated with
circumvallate papillae .
• Mediated by
glossopharyngeal nerve.

• The fifth taste sense, umami
was recently added.
• It is triggered by glutamate and
particularly by the
monosodium glutamate (MSG)
used so extensively in Asian
cooking.
• The taste is pleasant,aromatic
& taste depends on
concentration of salt.

Nerve supply

Taste Pathway

• 7th
nrv- geniculate ganglion
• 9 nrv- petrosal ganglion
• 10 nrv- nodose ganglion

Taste Receptors & Transduction
• The salty taste is triggered by NaCl. Salt-sensitive taste is
mediated by a Na+
-selective channel known as ENaC.
• The entry of Na+
into the salt receptors depolarizes the
membrane, generating the receptor potential.

•The sour taste is triggered by protons (H+
ions). ENaCs
permit the entry of protons and may contribute to the
sensation of sour taste.
• The H+
ions can also bind to and block a K+
-sensitive
channel. The fall in K+
permeability can depolarize the
membrane.
•Umami taste is due to activation glutamate receptor,
mGluR4, in the taste buds.www.indiandentalacademy.com

•Bitter taste is produced by a variety of compounds like
quinine.
• Many of these are poisons, and bitter taste acts via T2R
family of G- protein couple receptor.
• In some cases, these receptors couple to the
heterotrimeric G protein, gustducin.
• Gustducin acts via cAMP and inositol phosphates which
could lead to depolarization.
• Some bitter compounds bind to and block K+
-selective
channels.

•Substances that taste sweet also act via the G protein
gustducin.
•The T1R3 family of G protein-coupled receptors is expressed
by about 20% of taste cells, some of which also express
gustducin.
• Sugars taste sweet, but so do compounds such as saccharin
that have an entirely different structure.
• natural sugars such as sucrose and synthetic sweeteners act
via different receptors on gustducin.
• Like the bitter-responsive receptors, sweet-responsive
receptors act via cyclic nucleotides and inositol phosphate
metabolism.

• Abnormalities in Taste Detection
• Ageusia- absence of the sense of taste
• Hypogeusia -diminished taste sensitivity
• Dysgeusia or parageusia -unpleasant perception of taste
causes a metallic, salty, foul, or rancid taste.
•These abnomalities can be caused by damage to chorda
tympani or glossopharyngeal nerve.
• Neurological disorders such as Bell palsy, multiple
sclerosis.

• Infections like meningoencephalopathy can also cause
problems with taste sensitivity.
• Ageusia can also be an adverse side effect of various
drugs including cisplatin and captopril, antidepressants
like amitriptyline or vitamin B3 or zinc deficiencies.
• Aging and tobacco abuse also contribute to
diminished taste.

References
• B.D.Chourasia.Human Anatomy Regional & Applied Dissection
and clinical volume 3 Head,Neck and brain 4th
edition 2004
• Orbans Oral Histology and Embryology 13th
edition 267-270.
• Ganong’s Textbook of Medical Physiology 23rd
edition.
• Human Oral Mucosa development , structure and function.
• Ten Cate’s Oral Histology Development, Structure and Function.

Thank you

Taste bud/certified fixed orthodontic courses by Indian dental academy

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