Final answer:
The lunula is the white, crescent-shaped area at the base of the nail, visible due to a reflection of light on the thick epithelium which is part of the nail matrix where the nail growth originates.
Step-by-step explanation:
The lunula is the half-moon shape at the base of the nail that appears white due to a reflection of the light at the point where the thick epithelium over the nail matrix is located.
The nail bed, being rich in blood vessels, usually appears pink except at the base where the lunula is found. The lunula is made up of a crescent-shaped layer of thick epithelium and forms part of the nail matrix, which is responsible for nail growth due to a matrix of proliferating cells from the stratum basale.
This area does not have the underlying capillaries that give the rest of the nail bed its pink color, causing the lunula to appear whiter by contrast.
The nail matrix is a critical structure in the formation and growth of the nail, located at the nail root, which is under the skin at the near, or proximal, end of the nail.
The nail body, formed on the nail bed, serves as a protective unit and aids in the manipulation of small objects. It is composed of densely packed dead keratinocytes, providing the hard surface we're familiar with.