The external canal is a unique environment that has an elaborate mechanism for self-cleaning and protection. The fundamental basis of this is the epithelial migration of the desquamating layers of the keratinizing epithelium that lines the entire canal and ear drum. This migratory movement results in a "conveyor belt" effect where the dead skin is moved out of the bony ear canal to the cartilaginous portion, where it is lifted off with the help of glandular skin secretions and the hairs of the canal to form what we call "ear wax." The ear wax has numerous protective properties and is essential to the health of the external ear. The protective properties are due to chemical properties of the wax, in addition to intrinsic chemical secretions by the sebaceous and cerumen apocrine glands. The protection also comes from a diverse population of organisms that exist in the external ear that are usually saprophytic, commensal, and symbiotic, but in some cases, they can become parasitic and pathologic. Detection and quantification of the members of this biome has been difficult, and their overall role in the normal biome of the ear and their transition into pathogens remain an area of active research and investigation.
Keywords: Ear canal; External auditory canal; Wet wax.
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