Histology And Integumentary System Practice Test

Melanin production happens in specialized pigment-producing cells called melanocytes, and these cells reside in the deepest layer of the epidermis, the stratum basale, right along the basement membrane. Melanocytes extend processes that transfer pigment-filled melanosomes to neighboring keratinocytes, which then carry the pigment upward as the epidermis turns over. This basal-layer location explains why melanin distribution begins there and how it helps shield skin cell nuclei from UV damage as cells migrate through the upper layers. The other layers are made mainly of keratinocytes at different stages of differentiation—stratum corneum is the outer, dead layer; stratum granulosum contains keratinocytes with granules; and stratum lucidum is a thin layer seen only in thick skin.