Which layer of the hair contains cells that produce melanin?

The cortex is the correct answer because it is the middle layer of the hair shaft and is primarily responsible for the hair’s strength, color, and texture. This layer contains the majority of the hair’s pigment, which is melanin. Melanin is produced by cells called melanocytes, which are located within the cortex. It provides the hair with its color, ranging from blonde to black, depending on the type and amount of melanin present.

Understanding the structure of the hair helps clarify the role of each layer. The cuticle, for example, is the outermost, protective layer and does not contribute to pigmentation. The medulla is the innermost layer, which may or may not be present in all hair types and generally does not play a significant role in color. The follicle, while crucial for hair growth and overall health, is not part of the hair strand itself but instead is the structure from which the hair grows. Hence, the cortex is specifically where melanin production occurs, making it the foundational answer to the question.