“Den” of leaves
Dendritic cells get their name from their surface projections, which somewhat resemble the dendrites of neurons, the branchlike extensions that increase the surface of a cell body and receive information from other neurons.
Dendritic cells are found in most tissues of the body, most abundantly in those that interface between internal and external environments, such as the skin, lungs and lining of the gastrointestinal tract. Here, they’re suitably placed to serve their primary function, which is to continuously sample their surroundings for antigens, such as dead cells or invasive microbes. They are a key player in the body’s immune response system.
Once exposed to an antigen, say a virus, the sheets of the dendritic cell entrap it so that it can be degraded by internal lysosomes into peptide fragments and then redisplayed to circulating T cells, which develop the appropriate immune response.
The image above is an artistic rendering, based on ion abrasion scanning electron microscopy developed at the National Institutes of Health.