How are the cells in the epidermis supplied with nutrients?

The cells in the epidermis receive their nutrients primarily through the process of diffusion from the underlying dermis, which contains blood vessels. While the epidermis itself is avascular (lacks blood vessels), the dermal layer provides necessary nutrients to the epidermal cells by allowing small molecules, oxygen, and nutrients to diffuse through the basement membrane. This diffusion is essential for cellular health, as the epidermal cells are reliant on these nutrients to sustain their growth, repair, and functions.

The involvement of dermal papillae is also important, as these structures help to increase the surface area for interaction between the epidermis and dermis, enhancing nutrient exchange. However, nutrient delivery is fundamentally dependent on the network of blood and lymph vessels found in the dermis, which serves as the primary source of nourishment for the epidermal cells.