Physiology, Sebaceous Glands

The sebaceous gland is integral to the structure and function of the skin, providing 90% of its surface lipids. While much of the focus relating to the sebaceous gland comes from its central role in acne vulgaris, several new functions have come to light that highlight this versatile cellular unit’s complex role in skin homeostasis. The sebaceous gland is special in at least 2 ways. Firstly, the product of this gland is synthesized via holocrine secretion, a unique method characterized by the purposeful self-destruction of its primary cellular unit, the sebocyte. Secondly, despite being of epithelial origin and possessing numerous hormone receptors, sebocytes engage in lipid synthesis and metabolism, a job normally reserved for adipocytes. Thus, the sebaceous gland can be considered a hormonal target and an endocrine organ. The production of sebum is the most important function of the sebaceous gland in humans. Unique to the sebaceous gland is the production of squalene and certain fatty acids. Sebum production is critical for maintaining skin homeostasis, lubrication, and physiological defense against environmental and infectious insults (see The Common Integument, Section of Skin).