coenocyten

A coenocyte is a multinucleate cell in which many nuclei share a common cytoplasm within a single plasma membrane. The term comes from Greek roots meaning “common cell.” Coenocytes arise when nuclear divisions occur without corresponding cytokinesis, so the cytoplasm is not partitioned into separate cells.

Most coenocytes form by mitotic nuclear divisions in which cytokinesis is inhibited, producing a large, continuous cytoplasmic mass with numerous nuclei. This can occur during normal development or in response to environmental conditions. In some organisms, coenocytic tissues arise early in growth and remain unseptated, while in others septa may form only after a period of coenocytic growth.

Coenocytic organization is widespread across life forms. In plants and algae, many species have coenocytic thalli or plasmodia, such as certain green algae (for example, Caulerpa) and brown algae, where the body consists of a single, multinucleate cell. In fungi, many groups (notably the Zygomycota and some oomycetes) possess coenocytic hyphae that lack cross walls (septa) along parts of their length, enabling rapid cytoplasmic streaming and growth. In slime molds, the plasmodium is a classic coenocytic structure containing thousands of nuclei.

In animals, true coenocytes are uncommon; many multinucleate tissues result from cell fusion to form syncytia rather than from nuclear divisions without cytokinesis. Consequently, the term coenocyte is most frequently used in botany and mycology, with the related concept of syncytium describing similar multinucleate tissues formed by fusion or division.

See also: syncytium, hypha, plasmodium.