The central process passes toward the deep extremity of the bud, and there ends in single or bifurcated varicosities. The peripheral end of the cell terminates at the gustatory pore in a fine hair filament, the gustatory hair. The gustatory (taste) cells, which are chemoreceptors, occupy the central portion of the bud they are spindle-shaped, and each possesses a large spherical nucleus near the middle of the cell. Some, however, are found in the interior of the bud between the gustatory cells. The supporting ( sustentacular cells) are mostly arranged like the staves of a cask, and form an outer envelope for the bud. The bud is formed by two kinds of cells: supporting cells and gustatory cells. They are characterized by increased keratinisation and are involved in the mechanical aspect of providing abrasion. Filiform papillae - the most numerous type but do not contain taste buds.They are associated with ducts of Von Ebner's glands, and are innervated by the glossopharyngeal nerve. They are arranged in a circular-shaped row just in front of the sulcus terminalis of the tongue. Circumvallate papillae - there are only about 10 to 14 of these papillae on most people, and they are present at the back of the oral part of the tongue.Innervated by facial nerve (anterior papillae) and glossopharyngeal nerve (posterior papillae). Foliate papillae - these are ridges and grooves towards the posterior part of the tongue found at the lateral borders.These are present mostly at the dorsal surface of the tongue, as well as at the sides. Fungiform papillae - as the name suggests, these are slightly mushroom-shaped if looked at in longitudinal section.There are four types of lingual papillae all except one contain taste buds: The taste buds on the tongue sit on raised protrusions of the tongue surface called papillae. The average lifespan of these are estimated to be 10 days. On average, the human tongue has 2,000-10,000 taste buds. The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via the seventh, ninth and tenth cranial nerves. These are located on top of the taste receptor cells that constitute the taste buds. Via small openings in the tongue epithelium, called taste pores, parts of the food dissolved in saliva come into contact with the taste receptors.
A popular myth assigns these different tastes to different regions of the tongue in fact, these tastes can be detected by any area of the tongue. These structures are involved in detecting the five elements of taste perception: saltiness, sourness, bitterness, sweetness and umami. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the cheek, and epiglottis. Taste buds contain the taste receptor cells, which are also known as gustatory cells.
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