Intercellular lipids are critical for the skin's barrier function and are primarily found in which layer?

Intercellular lipids play an essential role in maintaining the skin's barrier function, which protects against water loss and environmental damage. The stratum corneum, which is the outermost layer of the skin, is primarily composed of dead skin cells (corneocytes) that are embedded in a matrix of intercellular lipids. These lipids, including ceramides, cholesterol, and fatty acids, serve to fill the spaces between the cells, creating a strong barrier that prevents transepidermal water loss and provides hydration.

The presence of these intercellular lipids is critical because they help to retain moisture in the skin, making it more resilient and less prone to irritation or infections. This layer is often the focus of skincare products aimed at enhancing skin barrier function, as restoring lipid levels in the stratum corneum can significantly improve skin health and appearance. Other layers, such as the viable epidermis, dermis, and hypodermis, do have important functions and components but do not primarily serve as the site for intercellular lipids contributing to barrier function in the same way as the stratum corneum.