What is the Origin of Epidermal Turnover?

The term combines "epidermal," from the Greek epi (upon) and derma (skin), referring to the top layer of skin, with "turnover," a term from economics and biology describing the rate at which a system is replaced or renewed.

What is the Mechanism of Epidermal Turnover?

The process is governed by complex signaling pathways, including growth factors and retinoid receptors, which regulate the mitotic activity of the basal layer. Hormones, notably estrogens and androgens, influence the rate of keratinocyte proliferation and differentiation. A complete cycle typically takes around 28 days in young adults, but disruption or slowing of this mechanism leads to accumulation of dead cells and impaired barrier function.

Epidermal Turnover

Meaning

Epidermal turnover, also known as cell renewal or desquamation, is the continuous physiological process by which the outermost layer of the skin, the epidermis, regenerates itself. This involves the proliferation of basal keratinocytes, their differentiation, upward migration, and eventual shedding as dead corneocytes from the skin surface. The rate of this turnover is a critical determinant of skin health, barrier function, texture, and appearance, often slowing significantly with advancing age and hormonal shifts.