What is a Merkel cell?

Overview of Merkel cells

Merkel cells are found in the  epidermis epidermis The outermost layer of the two main layers that make up the skin (the dermis is the deeper layer). Merkel cells normally exist in the bottom (basal) layer of the epidermis, about 0.1 mm from skin's surface.  (outer layer of the skin). They were originally described in the late 1800s by Friedrich Merkel, a German anatomist. He found these cells at high density in the paws of rats and surmised they may serve as “touch cells”.  Over 100 years later, although not all of the functions of Merkel cells are known, it is quite clear that they do indeed serve as touch cells and relay touch-related information such as texture and pressure to the brain. While they are present in human skin at varying levels according to body site, they are at highest density on the fingertips and lips/face where touch sensation is most acute. In addition, they produce certain hormones and are sometimes referred to as  neuroendocrine neuroendocrine Neuroendocrine refers to the type of cells that make up Merkel cell carcinoma. "Neuro-" means that these cells have some sensory function related to the nervous system, while "endocrine-" refers to hormonal types of cells. Merkel cells have both such features.  cells, although the reasons they produce certain hormones is unknown.

Merkel cell diagram

In the below illustration of a cross-section of skin, normal Merkel cells are shown in red and connect to nerves shown in yellow. The structures drawn include the epidermis (upper third), dermis dermis The deeper layer of the two main tissue layers that make-up the skin. The dermis is below the epidermis. Merkel cells are normally in the epidermis. In MCC, they grow and invade into the dermis and deeper structures and vessels. (middle), and deeper adipose (fatty) layer. Arteries are depicted as red and veins are blue.