Which of the following cells transfers pigment granules to adjacent epidermal cells?
A.
Melanocytes
B.
Merkel cells
C.
Langerhans cells
D.
Keratinocytes
The correct answer and Explanation is :
The correct answer is A. Melanocytes.
Explanation:
Melanocytes are specialized cells located in the epidermis, the outermost layer of the skin. Their primary function is to produce and transfer pigment granules called melanosomes to adjacent epidermal cells, specifically keratinocytes. This process is crucial for determining skin color and protecting the skin from ultraviolet (UV) radiation.
Here’s a detailed look at how melanocytes work:
- Pigment Production: Melanocytes contain organelles known as melanosomes, where melanin, the pigment responsible for skin color, is synthesized. Melanin comes in various forms, including eumelanin (brown and black pigments) and pheomelanin (yellow and red pigments).
- Transfer of Pigment: Once melanin is produced, it is packaged into melanosomes, which are then transferred to the surrounding keratinocytes through a process called dendritic transfer. Melanocytes have long, branching projections that extend between keratinocytes, allowing the transfer of melanosomes into these cells.
- Distribution of Pigment: Once inside the keratinocytes, melanosomes distribute the pigment throughout the cell. This distribution helps protect the DNA in keratinocytes from UV radiation by absorbing and dissipating harmful rays, thereby reducing the risk of skin damage and skin cancer.
- Skin Color Variation: The amount and type of melanin produced by melanocytes contribute to the variety of skin colors observed in different individuals. Genetic factors largely determine the number and activity of melanocytes, influencing skin color variations.
In contrast, Merkel cells are involved in sensory reception, Langerhans cells are part of the immune system and help in antigen presentation, and keratinocytes are the primary cells in the epidermis responsible for forming a protective barrier and producing keratin. However, keratinocytes do not transfer pigment granules to other cells; that function is specifically performed by melanocytes.