UNSW Embryology
Development of Taste
© Dr Mark Hill (2007)
Introduction
These notes introduce the development of the sense of taste which can divided into five basic tastes: bitter, salty, sweet, umami (savoury) and sour.
The human tounge and taste: a, Taste buds (left) are composed of 50–150 taste-receptor cells (TRCs) depending on the species, distributed across different papillae.
b, Recent molecular and functional data shown there is no tongue 'map' modalities are present in all areas of the tongue.
(Image reprinted by permission from Macmillan Publishers Ltd: Nature 444, 288-294 16 November 2006 | Reference)
These notes cover development of taste, not the muscular tongue. (More? Head and Neck Development - Tongue)
Page Links:
Introduction | Some Recent Findings | stage 13/14 embryo | stage 22 embryo |
Reading | Computer Activities | Objectives | Development Timing | Development Overview |
Adult Taste Bud Cells | Taste Receptors | Taste Pathway | Developmental Genes | References |
WWW Links | Glossary
Some Recent Findings
Iwatsuki K, Liu HX, Grunder A, Singer MA, Lane TF, Grosschedl R, Mistretta CM, Margolskee RF.
Wnt signaling interacts with Shh to regulate taste papilla development. Proc Natl Acad Sci U S A. 2007 Feb 6
"Wnt and Shh signaling pathways are critical for the development and maturation of many epithelial tissues...Wnt/beta-catenin signaling and interactions between the Wnt and Shh pathways play essential roles in the development of fungiform papillae."
Breslin PA, Huang L.
Human taste: peripheral anatomy, taste transduction, and coding. Adv Otorhinolaryngol. 2006;63:152-90.
Schoenfeld MA, Neuer G, Tempelmann C, Schussler K, Noesselt T, Hopf JM, Heinze HJ.
Functional magnetic resonance tomography correlates of taste perception in the human primary taste cortex. Neuroscience. 2004;127(2):347-53.
"glutamate receptors on the tongue might be processed in an exclusive way in the primary taste cortex rather than as a combination of inputs from the classical taste receptors."
Stage 13/14 Embryo
There are no Stage 13/14 sections which relate to development of taste. (More? Head and Neck Development - Tongue)
Stage 22 Embryo
Section (B4) through head showing tongue and head structures.
Reading
Bookshelf
Molecular Biology of the Cell (4th ed.) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002.
Sensory Epithelia
Neuroscience (2nd ed.) Purves, Dale; Augustine, George.J.; Fitzpatrick, David; Katz, Lawrence.C.; LaMantia, Anthony-Samuel.; McNamara, James.O.; Williams, S. Mark, editors.
Sunderland (MA): Sinauer Associates, Inc. 2001
Taste Receptors and the Transduction of Taste Signals |
Objectives
- Understand the embryonic origin of sensory epithelia.
- Understand the timecourse in the development of taste.
- Understand how taste is percieved through receptors.
- Understand the structure and location of tastebuds.
- Understand the pathway of taste perception.
Computer Activities
UNSW Embryology:
Embryo Images Unit:
Embryo Images Online
Development Timing
Week 6 - gustatory papilla, caudal midline near the foramen caecum
Week 6-7 - nerve fibers approach the lingual epithelium
Week 8 - nerves penetrate epitheilai basal lamina and synapse with undifferentiated, elongated, epithelial cells (taste bud progenitor cell)
Week 10 - shallow grooves above the taste bud primordium
Week 12 - first differentiated epithelial cells (Type II and III)
Week 12 -13 - maximum synapses between cells and afferent nerve fibers
Week 14-15 - taste pores develop, mucous
Week 18 - substance P detected in dermal papillae, not in taste bud primordia
3rd Trimester -
(These are Human embryonic timings, not clinical which is based on last menstral period +2 weeks)
Sources: Witt M, Reutter K., 1996, Witt M, Reutter K., 1997
Adult Taste Bud Cells
Electron Microscope Characterization
Type I cells, characterized by apically located dense secretory granules.
Type II cells, electron-dark cells with well developed endoplasmic reticulum and many apical mitochondria, with foot-like processes containingdense-cored vesicles (120-200 nm in diameter)
Type III cells, electron-dense cells containing large numbers of dense-cored vesicles (80-150 nm in diameter).
Sources: Witt M, Reutter K., 1996
Taste Receptors
Two opposing views of how taste qualities are encoded in the periphery.
a, In the labelled-line model, receptor cells are tuned to respond to single taste modalities — sweet, bitter, sour, salty or umami — and are innervated by individually tuned nerve fibres. In this case, each taste quality is specified by the activity of non-overlapping cells and fibres.
b,c, Two contrasting models of what is known as the 'across-fibre pattern'. This states that either individual TRCs are tuned to multiple taste qualities (indicated by various tones of grey and multicoloured stippled nuclei), and consequently the same afferent fibre carries information for more than one taste modality (b),
or that TRCs are still tuned to single taste qualities but the same afferent fibre carries information for more than one taste modality (c). In these two models, the specification of any one taste quality is embedded in a complex pattern of activity across various lines. Recent molecular and functional studies in mice have demonstrated that different TRCs define the different taste modalities, and that activation of a single type of TRC is sufficient to encode taste quality, strongly supporting the labelled-line model.
(Image and text above reprinted by permission from Macmillan Publishers Ltd: Nature 444, 288-294 16 November 2006 | Reference)
Umami historical Japanese word describing the taste in seaweed, used to describe the taste of "savoury".
Taste Pathway
Taste Buds
Anterior 2/3 tongue - Cranial nerve VII
Posterior 1/3 tongue - Cranial nerve IX
Epiglottis - Cranial nerve X
Brainstem - Solitary Nucleus
Thalamus - Ventral Posterior Medial (VPM) Nucleus
Cortex (Gustatory)
Insula
Frontal
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(More? Neuroscience - Organization of the human taste system)
Reward - dopamine in the nucleus accumbens?
Developmental Genes
sonic hedgehog Iwatsuki K, Liu HX, Grunder A, Singer MA, Lane TF, Grosschedl R, Mistretta CM, Margolskee RF.
Wnt signaling interacts with Shh to regulate taste papilla development. Proc Natl Acad Sci U S A. 2007 Feb 6
Wnt Iwatsuki K, Liu HX, Grunder A, Singer MA, Lane TF, Grosschedl R, Mistretta CM, Margolskee RF.
Wnt signaling interacts with Shh to regulate taste papilla development. Proc Natl Acad Sci U S A. 2007 Feb 6
Sox2 Tadashi Okubo, Larysa H. Pevny, and Brigid L.M. Hogan
Sox2 is required for development of taste bud sensory cells. Genes Dev. 2006;20 2654-2659 "Sox2 is expressed in basal epithelial cells of the tongue, with high levels in taste bud placodes, fungiform papillae, and mature taste cells, and low levels in filiform papillae."
(More? OMIM Sox2)
References
Reviews
Breslin PA, Huang L.
Human taste: peripheral anatomy, taste transduction, and coding. Adv Otorhinolaryngol. 2006;63:152-90.
Chandrashekar J, Hoon MA, Ryba NJ, Zuker CS
The receptors and cells for mammalian taste. Nature. 2006 Nov 16;444(7117):288-94. Review.
Sbarbati A, Crescimanno C, Merigo F, Benati D, Bernardi P, Bertini M, Osculati F.
A brief survey of the modifications in sensory-secretory organs of the neonatal rat tongue.
Biol Neonate. 2001 Jul;80(1):1-6.
Witt M, Reutter K.
Scanning electron microscopical studies of developing gustatory papillae in humans.
Chem Senses. 1997 Dec;22(6):601-12.
Articles
Iwatsuki K, Liu HX, Grunder A, Singer MA, Lane TF, Grosschedl R, Mistretta CM, Margolskee RF.
Wnt signaling interacts with Shh to regulate taste papilla development. Proc Natl Acad Sci U S A. 2007 Feb 6
Mistretta CM, Liu HX.
Development of fungiform papillae: Patterned lingual gustatory organs. Arch Histol Cytol. 2006 Dec;69(4):199-208.
Liu HX, Maccallum DK, Edwards C, Gaffield W, Mistretta CM.
Sonic hedgehog exerts distinct, stage-specific effects on tongue and taste papilla development. Dev Biol. 2004 Dec 15;276(2):280-300.
Schoenfeld MA, Neuer G, Tempelmann C, Schussler K, Noesselt T, Hopf JM, Heinze HJ.
Functional magnetic resonance tomography correlates of taste perception in the human primary taste cortex. Neuroscience. 2004;127(2):347-53.
Witt M, Reutter K.
Embryonic and early fetal development of human taste buds: a transmission electron microscopical study.
Anat Rec. 1996 Dec;246(4):507-23.
Search PubMed: Feb 2007 "taste development" 1,593 reference articles of which 200 were reviews.
Search PubMed Now: taste development |
smell development
Glossary of Terms
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Comments
These notes introduce the development of the sense of taste.
Current research appears to have displaced the historic concept of a tounge "map".
A study in rat suggests that neonatal changes in circumvallate papillae may result in postnatal changes in "taste".
(More? Sbarbati A, etal, 2001)
In frogs, a large taste disc (TD) is the largest vertebrate gustatory organ.
Postnatally, the sense of taste is also closely related to the sense of smell.
These notes cover development of taste, not the muscular tongue. (More? Head and Neck Development - Tongue)
Please email Dr Mark Hill if you wish to make a comment about this current project.
