Keratinization

Keratinization — the process by which skin cells called keratinocytes mature, fill with the protein keratin, and move toward the surface to form the tough, protective outer layer of the epidermis. This gradual hardening creates the stratum corneum, the skin's first line of defense against water loss and external irritants.

Key points

• Keratinocytes originate in the basal layer and change shape and composition as they move upward.
• By the time cells reach the surface they are flattened, dead, and packed with keratin.
• Proper keratinization is essential for a strong, resilient skin barrier.
• Abnormal keratinization can contribute to conditions involving rough, thickened, or clogged skin.
• The process works alongside cell turnover and desquamation to keep the barrier renewing itself.

Frequently asked

What is keratin's role in the skin?

Keratin is a structural protein that gives the outer skin layer its strength and helps protect against moisture loss and outside irritants.

What happens when keratinization goes wrong?

Irregular keratinization can lead to a build-up of cells that appears as rough or thickened skin, or that contributes to clogged pores, depending on the underlying cause.

Related topics

• What Is a Humectant?
• What Is the Skin Barrier?

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.