Which part of the hair contains melanin?

The cortex of the hair is the part that contains melanin, which is the pigment responsible for the color of the hair. Melanin is produced by specialized cells called melanocytes, and it is deposited in the cortex, influencing the hair's shade and color intensity. The cortex is the thickest layer of the hair shaft, situated between the outer cuticle and the inner medulla (if present), playing a vital role in determining the hair's overall characteristics.

The medulla is often absent in finer hair types and does not contain melanin. The cuticle, on the other hand, is the outermost layer and serves primarily as a protective barrier; it does not play a role in pigmentation. The hair follicle is the structure in the skin from which the hair grows, containing cells that can produce hair but does not contain melanin itself. Therefore, the cortex is the only part of the hair shaft that directly contributes to its pigmentation.