In which layer are melanin granules primarily located?

Melanin granules are primarily located in the stratum basale, which is the deepest layer of the epidermis. This layer contains melanocytes, the cells responsible for the production of melanin. Melanin is a pigment that gives skin its color and provides protection against ultraviolet (UV) radiation.

While the stratum spinosum does contain some keratinocytes, it is primarily known for its spiny appearance due to desmosomal connections between cells. Most melanin granules, however, are produced in the stratum basale and then transferred to neighboring keratinocytes, where they contribute to skin pigmentation.

The stratum granulosum plays a role in the keratinization process, where cells begin to lose their nuclei and flatten out, while the stratum corneum is the outermost layer of dead cells that have lost their nuclei and do not contain living melanocytes or melanin. Thus, the correct choice reflects a more accurate understanding of where melanin production and distribution primarily occur within the skin layers.