Milady Esthetics State Board Complete Practice Test 2026

The stratum corneum, or the keratinized layer of the skin, typically consists of about 15 to 20 layers of dead skin cells, which are flat and filled with keratin. This layer plays a crucial role in protecting the underlying tissues from environmental factors, pathogens, and water loss.

The cells in the stratum corneum are continually being shed and replaced, which is essential for skin health. Having this specific range of 15 to 20 layers allows the skin to maintain its barrier function effectively while still enabling the process of desquamation, where older cells are sloughed off to make way for newer ones.

Understanding the thickness and structure of the stratum corneum is important for estheticians, as it influences how products penetrate the skin and how various treatments can be performed.