sebocytes

Sebocytes are specialized epithelial cells that form the sebaceous glands, which are distributed in the dermis and usually associated with hair follicles. They are holocrine secretory cells: mature sebocytes accumulate lipid droplets and, upon disintegration, release sebum into the glandular lumen and through the follicular duct.

Sebum is a lipid-rich secretion that coats the skin and hair, helping to retain moisture and providing antimicrobial properties. Composition includes triglycerides, wax esters, squalene, and free fatty acids. Secretory cycle involves new cells differentiating from basal progenitors at the gland periphery; as they mature they accumulate lipids, then rupture to release contents, with continual regeneration of sebocytes.

Regulation is influenced by hormones and signaling pathways. Androgens stimulate sebum production, while estrogens can counterbalance this effect. Retinoids can modulate gland size and activity. Transcription factors such as PPAR gamma promote lipid accumulation and sebocyte differentiation, and Wnt signaling also influences sebaceous lineage.

Clinical relevance includes disorders of sebum production and sebaceous gland function. Excessive sebum production is associated with acne vulgaris, where altered sebum composition, follicular plugging, and inflammatory responses contribute to pathology. Sebaceous hyperplasia is a benign enlargement of glands; other sebaceous disorders are relatively uncommon. Treatments such as retinoids and hormonal therapies aim to reduce sebaceous gland activity or normalize keratinization, with isotretinoin being a potent option that markedly decreases gland size and sebum output.

Sebum serves to lubricate and protect the skin and hair and may contribute to antimicrobial defense through lipid components.