Sebaceous Glands: Structure, Sebum Function, and Clinical Relevance

Structure and Secretion

Sebaceous glands are holocrine glands attached to hair follicles (except on lips, glans, labia minora). They secrete sebum—a lipid mixture (triglycerides, wax esters, squalene, cholesterol).

Functions

• Skin barrier hydration and acid mantle maintenance.
• Antimicrobial peptides (sapienic acid).
• Thermoregulation (lipid film reduces evaporative loss).
• Pheromone precursor.

Disorders

• Acne vulgaris (hyperkeratinization + sebum + C. acnes).
• Seborrheic dermatitis (Malassezia overgrowth on sebum‑rich areas).
• Sebaceous hyperplasia, adenoma, carcinoma (rare).

Androgens upregulate sebum; isotretinoin dramatically suppresses gland size/output.