Cell

Definition

The smallest structural and functional unit of living organisms, bounded by a membrane and containing genetic material, cytoplasm, and organelles capable of metabolism, growth, and reproduction. In arthropods, cells form specialized tissues including the epidermis, fat body, hemocytes in hemolymph, and the columnar cells of the midgut epithelium that secrete digestive enzymes and absorb nutrients.

Etymology

From Latin cella, meaning small room or chamber, adopted in 17th-century biology to describe the microscopic compartments observed by Robert Hooke in cork tissue.

Example

Insect hemocytes—phagocytic cells circulating in the hemolymph—recognize and encapsulate foreign bodies such as parasitoid wasp eggs, forming a multicellular sheath that melanizes and kills the invader.

Related Terms

• tissue
• organelle
• Cytoplasm
• Nucleus
• Membrane
• epithelium
• hemocyte
• Fat body

Usage Notes

In arthropod biology, 'cell' often appears in compound terms denoting specific cell types (oenocyte, nephrocyte, mycetocyte) or structural units (ommatidium, sensillum). Contrast with 'cell' in collection contexts, where it may refer to a compartment in an insect drawer or rearing container.