Taste buds are microscopic structures found in the epithelium of the fungiform, foliate and circumvallate papillae of the tongue; they are also found widely separated in the soft palate; epiglottis and the free edge of the vocal folds.
They are ellipsoid bodies embedded in an upright position in the epithelium of the mucous membrane. The taste bud is made up of supporting or sustentacular cells and neuroepithelial cells.
The peripheral supporting cells form the outer layer of the taste bud. These are curved narrow cells with an ellipsoid nucleus, which surrounds the central supporting cells which are shorter and straighter than the peripheral ones and rounded off on the distal end.
In some species the taste buds also contain basal supporting cells. These lie deep to the other supporting cells and are connected to them by means of processes.
The neuroepithelial cells lie among the supporting cells. These are slender cells thickened slightly in the region of the nucleus and resemble the central supporting cells. Each is characterized externally by a fine hair-like process called taste hair which projects through a minute opening in the epithelium called the taste pore. The inner end of the cells tapers to a fine process, which may be single or branched.
The sensory nerve fibre which convey gustatory impulses end within the taste buds in a network of varicose fibres called intragemmal fibres.
The terminations of the intragemmal fibres end directly on the cells. Some of the termination also end between the cells (inter gemmal fibres). Dissolved substances stimulate the sensory cells.
The lingual glands are situated partly below the mucous membrane, partly in the inter-muscular tissue, and are especially abundant on the root, on the margins and near the circumvallate papillae.
Those in the region of circumvallate papillae are the serous glands of Van Ebner. The remaining glands are all mucous glands.
