Changes

===Glands of the Ear Canal===

===Glands of the Ear Canal===

The apocrine glands in the ear canal are modified and known as ceruminous glands.  The material secreted into the ear canal, '''cerumen''' (or wax), is compromised of exfoliated epithelial cells (squames) and glandular secretions.  Sebaceous glands predominate distally and are largely responsible for the lipid component of cerumen.  The density of ceruminous glands increases proximally, towards the tympanic membrane.  The secretions of the ceruminous glands contain mucopolysaccharides and phospholipids.  Immunoglobulins IgA, IgG and IgM have been identified in canine cerumen, predominantly IgG.

The apocrine glands in the ear canal are modified and known as ceruminous glands.  The material secreted into the ear canal, '''cerumen''' (or wax), is compromised of exfoliated epithelial cells (squames) and glandular secretions.  Sebaceous glands predominate distally and are largely responsible for the lipid component of cerumen.  The density of ceruminous glands increases proximally, towards the tympanic membrane.  The secretions of the ceruminous glands contain mucopolysaccharides and phospholipids.  Immunoglobulins [[IgA]], IgG and IgM have been identified in canine cerumen, predominantly IgG.

The epithelial cells in the [[Skin - Anatomy & Physiology#Epidermis|stratum granulosum]] of the tympanic membrane migrate centripetally, and this migration comprises the natural cleaning mechanism keeping the tympanum free of debris.  The upward/distal migration of epithelial cells clears desquamated cells, secretions, debris and microbes. The more aqueous secretions of the ceruminous glands, present proximally, allow easier upward migration, whereas the higher lipid content of the distal secretions offers better barrier protection.

The epithelial cells in the [[Skin - Anatomy & Physiology#Epidermis|stratum granulosum]] of the tympanic membrane migrate centripetally, and this migration comprises the natural cleaning mechanism keeping the tympanum free of debris.  The upward/distal migration of epithelial cells clears desquamated cells, secretions, debris and microbes. The more aqueous secretions of the ceruminous glands, present proximally, allow easier upward migration, whereas the higher lipid content of the distal secretions offers better barrier protection.