Fat cells-below all the above stuff C. Melanocytes are located on the lowest layer of the epidermis, among the dividing basal cells. The pigment is located in little membrane-bounded vesicles inside the melanocyte. You can see these vesicles as black dots in the diagram scanned into our web page. The regular skin cells take up the vesicles of pigment in much the same way as an ameba eating something. When the cells on the surface of the skin have these bits of pigment, they look brown.
Sunlight stimulates the melanocytes to produce more pigment to give to the surrounding cells.
The number of melanocytes, their spacing, and the extent of their response to sunlight are genetically determined. We had a number of class comments about melanocytes. Here are some of them. The drug is doxycycleine. During pregnancy, hormones change and a person may look like they have a sun tan even if they don't because the hormones have an effect on melanocytes in certain places on the body.