Within the stratum basale there are also a few other important cell types found among the native keratinocytes. They are the melanocytes, merkel’s cells, and langerhan’s cells. These cells have descended from cell lines which had their origins elsewhere.As a group these are often referred to as clear cells, because, unlike keratinocytes, their cytoplasm appears unstained in most microscopic preparations.
Melanocytes are dendritic cells (cells with processes extending outward) containing melanin pigment and are of neural crest origin. Melanin pigment is released from processes of melanocytes and then taken up by the surrounding keratinocytes.
Merkel’s cells are either of epidermal or neural crest origin. They have clear cytoplasm, are found in the basal layer of the epidermis, are found adjacent to modified nerve endings, and may be neurosecretory.
Langerhan’s cells function as macrophages in the skin, presenting antigens to helper T-cells. Langerhan’s cells are dendritic cells, and they have their origin in the bone marrow.
