Difference Between Keratinocytes and Melanocytes

Keratinocytes vs Melanocytes
 

To understand the difference between keratinocytes and melanocytes, one must first understand the anatomy of skin. Skin is the largest organ of the body and acts a mechanical barrier between the underlying tissues and the external environment. Skin is mainly composed of two layers; outer- protective epidermis and inner-connective dermis. Epidermis contains few layers of epithelial cells and has no direct blood supply. The cells are nourished through the diffusion of nutrients from the underlying nutrient-rich blood supply. Inner epidermis contains cube-shaped, rapidly dividing cells, while the outer epidermis contains dead cells, which are shed and removed rapidly from the body. Dermis is lying under the epidermis and is composed of many elastin and collagen fibres with a great blood supply. Epidermis consists of four specialized cells types, namely; melanocytes, keratinocytes, Langerhans cells, and Grinstein cells. Out of these four cells, only melanocytes and keratinocytes are discussed in this article. The key difference between keratinocytes and melanocytes is that keratinocytes form hair and nails, whereas melanocytes are responsible for color of the skin. Further differences between both, keratinocytes and melanocytes, are discussed in detail, in this article

What are Keratinocytes?

Keratinocytes are the most abundant cell type in the epidermis. As the name implies, the keratinocytes are specialized in keratin production and the dead keratinocytes ultimately result in the keratinized layer forming hair and nails. Moreover, the keratinocytes influence the maturation of T cells by secreting IL-1 (also produced by macrophages) and hence keratinocytes help to increase the immunological actions in the body.

What are Melanocytes?

Melanocytes are the specialized cells found in the epidermis and mainly responsible for the production and dispersion of the pigment called melanin, which gives the color of the skin of various races. Usually, all the races have the same number of melanocytes, but the only reason for resulting different color skins is the different amount of melanin produced by each melanocyte. Tyrosinase enzyme in melanocytes plays a major role during the complex biochemical pathways which lead to the formation of melanin. If tyrosinase is fully functional, the resulting skin is very dark in color. However, in people with lighter skin color, two genetic factors are responsible to reduce the functioning capacity of tyrosinase; (a) much of the tyrosinase remains in inactive form and (b) tyrosinase action is inhibited by various inhibitors. As a result of these two factors, the melanin production is low. Melanin is an important pigment which can absorb the harmful UV rays emitted by Sun. Long time exposure to UV rays increases the production of melanin, thus resulting dark sites on the skin.

Difference between Keratinocytes and Melanocytes

What is the difference between Keratinocytes and Melanocytes?

• The amount of keratinocytes is very high when compared to the amount of melanocytes.

• Keratinocytes are responsible for the formation of keratin, whereas melanocytes produce melanin.

• Keratinocytes form hair and nails, whereas melanocytes responsible for color of the skin.

• Exposure to UV light stimulates the secretion of ∝-melanocyte stimulating hormone (∝-MSH) from keratinocytes and this ∝-MSH stimulates neighboring melanocytes to enhance the production of melanin.

• Keratinocytes provide mechanical protection and are also important immunologically. Melanocytes protect the skin from harmful UV rays.