CorpusHuman Anatomy
Special SensesReceptor

Taste buds

Calyculi gustatorii

Also known as: gustatory buds, taste pore, caliculi gustatorii

Onion-shaped clusters of 50–100 taste receptor, supporting and basal cells embedded in the epithelium of the tongue papillae, soft palate, pharynx and epiglottis, opening to the surface by a taste pore.

Show on body map Smell and Taste — Chemoreceptors

Overview

Number (adult)≈2 000–5 000 (up to ≈10 000)
Cells per bud50–100
Height≈50–70 µm
Taste cell lifespan≈8–12 days

An adult has ≈2 000–5 000 taste buds (wide individual variation, with estimates up to ≈10 000), most on the fungiform, foliate and circumvallate papillae of the tongue, with others on the soft palate, epiglottis, pharynx, larynx and upper oesophagus. Each bud is a barrel-shaped structure ≈50–70 µm tall spanning the thickness of the stratified squamous epithelium. At its apex a small opening, the taste pore, lets saliva-dissolved tastants reach the microvilli (taste hairs) of the receptor cells.

Taste buds contain 50–100 elongated cells of four types: type I (glial-like/supporting), type II (receptor cells for sweet, umami and bitter), type III (presynaptic cells for sour) and type IV (basal progenitor) cells. Taste cells are modified epithelial cells, not neurons; they synapse with the peripheral endings of afferent fibres of cranial nerves VII, IX and X that enter the base of the bud. Taste cells have a lifespan of only ≈8–12 days (some up to ≈3 weeks) and are continually replaced from basal cells — which is why taste usually recovers after burns or chemotherapy.

Contrary to the popular "tongue map", all five basic tastes can be detected wherever there are taste buds; regional differences in sensitivity are small. A taste bud contains cells responsive to different qualities, each cell typically tuned to one quality, and qualities are carried by largely separate ("labelled line") afferent channels.

Location

Epithelium of fungiform papillae (dorsum and tip of the anterior tongue), walls of circumvallate papillae and clefts of foliate papillae; also soft palate, epiglottis, pharynx and larynx.

Parts & subdivisions

  1. Taste receptor cells
    Type I (supporting/glial-like), type II (sweet, umami, bitter), type III (sour); see taste receptor cells.
  2. Basal cells (type IV)
    Undifferentiated progenitors at the base, regenerating taste cells every ≈8–12 days.
  3. Taste pore
    Apical opening into which microvilli project; contact point with dissolved tastants.
  4. Microvilli (taste hairs)
    Apical microvilli carrying taste receptors and channels.
  5. Afferent nerve fibres
    Gustatory fibres of VII, IX or X forming a plexus at the base and synapsing on type II (channel synapse) and type III (conventional synapse) cells.

Anatomy

Innervation

Anterior 2/3 of tongue — chorda tympani (VII) (cell bodies in the geniculate ganglion); soft palate — greater petrosal nerve (VII); posterior 1/3 including circumvallate papillae — glossopharyngeal nerve (IX) (inferior ganglion); epiglottis and pharynx — vagus (X) via the internal laryngeal nerve (inferior/nodose ganglion).

Histology

Pale-staining intraepithelial bud of elongated spindle-shaped cells with apical microvilli converging on a taste pore; basal cells at the base; nerve fibres entering from the lamina propria.

Development

Appear at ≈7–8 weeks, induced by gustatory nerve fibres (taste buds degenerate if denervated and reappear on reinnervation); functional before birth — the fetus swallows amniotic fluid.

Function

  • Detect the five basic tastes: sweet, umami, salty, sour, bitter
  • Assess nutritional value and potential toxicity of food
  • Trigger digestive reflexes (salivation, gastric secretion) and aversive reflexes (gagging)
Physiology

Thresholds (Guyton & Hall): bitter (quinine) ≈0.000008 M — far lower than sweet (sucrose) ≈0.01 M or salt (NaCl) ≈0.01 M, sour (HCl) ≈0.0009 M — reflecting the protective role of bitter detection against toxins. Taste adapts within a minute or two of continuous stimulation.

Clinical significance

Taste disturbance

Causes of ageusia/hypogeusia/dysgeusia: chorda tympani injury (middle-ear surgery, Bell palsy), IX injury (tonsillectomy), drugs (ACE inhibitors — captopril, metronidazole, lithium, chemotherapy), head and neck radiotherapy, zinc deficiency, xerostomia (Sjögren), viral infection (COVID-19) and smoking. Much apparent "loss of taste" is actually loss of retronasal smell.

Taste testing

Electrogustometry or filter-paper strips applied to each side of the tongue separately localise lesions (chorda tympani vs IX).

Test yourself

Which lingual papillae lack taste buds?
  1. Fungiform
  2. Filiform
  3. Foliate
  4. Circumvallate

Answer: Filiform

Filiform papillae — the most numerous — are keratinised and purely mechanical/tactile. Fungiform, foliate and circumvallate papillae carry taste buds.

More special senses questions

Compiled from standard anatomy and physiology references — see the Special Senses sources. For education only; not medical advice.