How Cerumen (Earwax) is Made
Composition and Production
Cerumen forms when glandular secretions from the outer two-thirds of the ear canal mix with exfoliated squamous epithelial cells. 1
Glandular Components
Sebaceous glands produce sebum, which contributes oily secretions to the cerumen mixture 1
Modified apocrine sweat glands (also called ceruminous glands) provide additional secretions that combine with the sebum 1
These ceruminous glands use a specialized apocrine secretion mechanism where the apical portion of the cell cytoplasm, surrounded by membrane, is pinched off and released into the ear canal 2
The pinching-off process involves actin filaments, cytokeratin 19, and cytokeratin 7 in the cellular machinery 2
Cellular Components
Sloughed epithelial cells from the cornified stratum of the external auditory canal epithelium mix with the glandular secretions 1, 3
As cerumen migrates laterally through the ear canal's natural self-cleaning mechanism (assisted by jaw movement), it may incorporate hair and other particulate matter 1
Location of Production
- Cerumen is produced exclusively in the outer two-thirds (cartilaginous portion) of the external auditory canal, not the inner third (bony portion) that ends at the tympanic membrane 1
Protective Functions
The resulting cerumen serves as a naturally occurring substance that cleans, protects, and lubricates the external auditory canal 1
Ceruminous glands secrete numerous antimicrobial proteins and peptides including beta-defensin-1, beta-defensin-2, cathelicidin, lysozyme, lactoferrin, MUC1, and secretory component of IgA, providing innate host defense against pathogens 2
The glands also secrete lipid vesicles that contribute to the protective barrier function 2