In which layer of the skin are mast cells primarily found?

Mast cells are primarily found in the dermis, which is the middle layer of the skin situated beneath the epidermis and above the hypodermis. This layer is rich in connective tissue and contains various cells, including fibroblasts, immune cells, and mast cells. Mast cells play a crucial role in the immune response, releasing histamines and other substances during allergic reactions and inflammatory processes. Their presence in the dermis allows them to effectively respond to pathogens and facilitate healing by promoting blood flow and attracting other immune cells to the site of injury or infection.

In contrast, the epidermis is the outermost layer of the skin, primarily composed of keratinocytes, and does not typically contain mast cells. The hypodermis, which lies beneath the dermis, consists of fat and connective tissue, also lacking mast cells in significant numbers. The stratum corneum, being the outermost sublayer of the epidermis, consists of dead skin cells that have no immune functions or mast cells. Therefore, the dermis is the correct answer, as it is the primary location where mast cells are found in the skin.