Papillae (from the Latin word meaning “nipple”) are present as hair-like, bulb-shaped, or domed structures on the tongue. The majority of papillae contain taste buds, which are essential for mediating the sense of taste. Four types of papillae are found in specific regions of the human tongue: circumvallate (or simply vallate), filiform, foliate, and fungiform. Circumvallate papillae are located the deepest in the mouth and look like large domes. This type of papillae is the biggest and may vary in number depending on the individual. Most people have 8 to 14 circumvallate papillae oriented in two rows, which are V-shaped and pointing toward the throat.
Structure and Function
To the naked eye, circumvallate papillae appear as large domed formations on the posterior one-third of the tongue. The structure of circumvallate papillae resembles an upside down “U” with the opened end serving as the attachment point to the body of the tongue. A microscopic view of these structures will show that the flat apical (top) surface is actually covered in tiny secondary papillae; the taste buds are housed in these smaller papillae. It is important to note that the sides of the circumvallate papillae “U” shapes are not attached to one another. They are instead surrounded by mucosa tissue, which forms slick walls called the vallum (Latin for “wall”). The trench that is created between the papillae is called the fossa, and it provides a channel for saliva flow.
Circumvallate papillae are most commonly known in association with von Ebner’s glands, specialized saliva glands located under the body of the tongue. These glands are named after the Austrian histologist Victor von Ebner (1842—1945) who discovered them. When we eat, von Ebner’s glands proceed to fill the empty fossa with saliva; when the saliva is swallowed, it washes away any taste molecules that were previously attached to the taste buds and prepares the papillae to detect new food molecules. This process allows circumvallate papillae to detect small changes in taste almost immediately. In order to handle this volume of taste information, the circumvallate papillae are connected to different cranial nerves than papillae on the anterior portion of the tongue. The saliva produced by von Ebner’s glands provides an important additional function: the enzyme lingual lipase is produced and secreted by these glands in order to begin lipid hydrolysis (the process of fat digestion) in the mouth.
There are few diseases that directly affect the structure or function of the circumvallate papillae. The most common form of loss of function is due to aging, which has been studied in both mouse and human models. This loss of taste buds seems to increase with age, but aging does not seem to affect some of the other papillae types.
Circumvallate papillae commonly become swollen or enlarged. Sometimes these swollen papillae are mistaken for something more serious (such as tumors), but for the most part it is not a serious issue and swelling will disappear after several days. This enlargement is suspected to be a result of viral infection, exposure to irritants, burning of the taste buds by hot food or drink, or by excessive smoking. Cigarette smoking may also affect the function of taste buds. A recent study by Jacob and colleagues (2014) has shown that current smokers and even former smokers are not able to distinguish between or identify bitter and nonbitter foods. Bitter foods can be easily identified at low concentrations by nonsmokers, yet as a result of toxicity produced by cigarette smoking on the tongue’s taste receptors, smokers and former smokers have a significantly decreased ability to identify this taste.
See also: Fungiform Papillae; Supertaster; Taste Aversion; Taste Bud; Taste System
Jacob, Nelly, Jean-Louis Golmard, & Ivan Berlin. (2014). Differential perception of caffeine bitter taste depending on smoking status. Chemosensory Perception, 7(2), 47—55.
Mistretta, Charlotte M., & Bruce J. Baum. (1984). Quantitative study of taste buds in fungiform and circumvallate papillae of young and aged rats. Journal of Anatomy, 138(2), 323—332. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1164072/pdf/janat00202-0126.pdf
Owen, David. (2015). Beyond taste buds: The science of delicious. National Geographic. Retrieved from http://ngm.nationalgeographic.com/2015/12/food-science-of-taste-text
Sbarbati, A., C. Crescimanno, & F. Osculati. (1991). The anatomy and functional role of the circumvallate papilla/von Ebner gland complex. Medical Hypotheses, 53(1), 40—44.