Which layer of the skin is primarily responsible for the skin's barrier function?

The stratum corneum is the outermost layer of the epidermis and plays a crucial role in the skin's barrier function. It consists of dead skin cells, also known as corneocytes, which are filled with keratin, a fibrous protein that provides structure and strength. This layer acts as a protective barrier that helps prevent the entry of pathogens, chemicals, and allergens while simultaneously reducing water loss from the body.

By retaining moisture and providing a defense against external aggressors, the stratum corneum is essential for maintaining overall skin health and integrity. It also influences the skin's texture and appearance, contributing to a smooth and supple surface. Therefore, understanding the function of the stratum corneum is vital for anyone studying esthetics, as it directly relates to skincare treatments and product formulations aimed at enhancing and supporting this protective layer.