Fungiform papillae are structures found on the tongue that play an important role in gustation or taste. Fungiform papillae get their name because they are shaped very much like mushrooms. They are found primarily on the tip of the tongue and run down the lateral aspect of the tongue. Taste buds, which are important in distinguishing between various tastes of food and liquids, are found within fungiform papillae, which then transmit information about taste to the brain via cranial nerve VII, also called the facial nerve.
There are four major types of papillae found on the human tongue. There is some disagreement among scientists as to whether all four types of papillae have taste buds associated with them. There is general agreement that fungiform papillae do have taste buds capable of sensing the five major tastes (sweet, sour, salty, bitter, and umami) to varying degrees.
The four major papillae found on the tongue include (1) filiform papillae, which are found in highest density on the anterior two-thirds of the tongue. There is general agreement that these papillae most likely do not have taste buds associated with them. (2) Fungiform papillae are found in highest density on the tip of the tongue and along the lateral aspects or sides of the tongue. These papillae tend to have a high concentration of taste buds associated with them. (3) Foliate papillae are found in highest density along the posterior lateral aspect of the tongue and in the back of the tongue. (4) Circumvallate papillae (or vallate) are found in highest density in the back of the tongue and down the middle or medial aspects of the tongue.
Anatomy and Innervation of Fungiform Papillae
Fungiform papillae are found on the tip of the tongue and along the lateral aspects of the tongue. It is estimated that the average human tongue has approximately 200 papillae in total. The papillae located at the tip of the tongue tend to have a greater number of taste buds associated with them (range of 1—18), while the fungiform papillae along the sides of the tongue generally have 1—9 taste buds associated with them. These papillae often appear as raised red spots on the tongue. It is possible for a person to determine the number of fungiform papillae on the tongue by using various dyes such as food coloring. A person who has a high density of these papillae on the tongue is considered to be a “supertaster.”
Taste receptors of the tongue follow a complex pathway to the brain for integration within the central nervous system. In summary, when taste buds within the fungiform papillae are stimulated, that information is then sent by the gustatory axons associated with the taste buds through cranial nerve VII to a specialized region in the brainstem called the gustatory nucleus. The gustatory nucleus is actually part of a larger structure known as the solitary nucleus. From this nucleus, information is carried to the primary sensory integration center of the brain, the thalamus, and then on to the primary sensory cortex within the cerebral hemispheres. This information is then acted upon and an appropriate response, if any is needed, is generated by the primary motor cortex.
Pathology of the Papillae
There are a number of common pathologies of the papillae of the tongue including transient lingual papillitis, which often affects the fungiform papillae. In this condition, the papillae are abnormally enlarged and individuals affected by this, depending on the density of the papillae on their tongue, may experience a burning or tingling sensation. Benign enlargement of the papillae is often caused by excessive smoking, canker sores, acid reflux (GERD), or irritation caused by excessively spicy or hot foods. In some rare cases, exposure to environmental toxicants such as insecticides or excessive alcohol can also cause enlarged papillae. Some vitamin B deficiencies can cause enlarged papillae in some individuals. A relatively rare condition known as depapillation can affect some individuals. In this case, the papillae of the tongue are damaged or lost, creating a condition that is also known as “bald tongue.” Bald tongue is often the result of nutritional deficiencies. Treatment for these conditions often consists of treating the underlying cause of the inflammation or loss of papillae.
Charles A. Ferguson
See also: Circumvallate Papillae; Facial Nerve; Taste System
Mistretta, Charlotte M., & Hong-Xiang Lieu. (2006). Development of fungiform papillae: Patterned lingual gustatory organs. Archives of Histology and Cytology, 69(4), 199—208.
Sollars, Suzanne I., Peter C. Smith, & David L. Hill. (2002). Time course of morphological alterations of fungiform papillae and taste buds following chorda tympani transection in neonatal rats. Journal of Neurobiology, 51, 223—236. http://dx.doi.org/10.1002/neu.10055
Srur, Ehab, Oliver Stachs, Rudolf Guthoff, Martin Witt, Hans Wilhelm Pau, & Tino Just. (2010). Change in the human taste bud volume over time. Auris Nasus Larynx, 37, 449—455.