Ceruminous glands

The skin lining the lateral third of the external acoustic meatus (the cartilaginous part) is thick and carries hairs, sebaceous glands and ceruminous glands — coiled tubular apocrine-type glands with wide lumina, cuboidal secretory cells containing yellow-brown pigment granules and an outer myoepithelial layer. Their ducts open into hair follicles or directly onto the canal surface. The medial (bony) part of the canal has thin skin without glands.

Their secretion combines with sebum and desquamated corneocytes to form cerumen. Earwax lubricates and waterproofs the canal, traps dust and insects, and is mildly antimicrobial (lysozyme, fatty acids, low pH). The canal epithelium migrates outward from the tympanic membrane, carrying wax to the entrance — a self-cleaning conveyor that cotton buds disrupt. Wet (sticky, brown) versus dry (flaky, grey) earwax is determined by a single-nucleotide variant of ABCC11; the dry type predominates in East Asian populations.