Melanocytes associate with the cells of the stratum basale. All races have about the same number of melanocytes, in association with keratinocytes (epidermal cells) in ratios of from 1:4 to 1:10 depending on the skin location. They secrete melanin in granules which are taken into the keratinocytes by endocytosis. Some melanin also remains in the interstitial space. Melanin helps protect the cells from UV radiation. Melanin varies in color among the races from a brown to a reddish tint. In addition to melanin, skin color is influenced by the presence of blood vessels and carotene. In Caucasian skin the melanin is broken down rapidly by enzymes from the keratinocytes.