<biology, embryology> Fusion of two previously separate cells occurs naturally in fertilization and in the formation of vertebrate skeletal muscle, but can be induced artificially by the use of Sendai virus or fusogens such as polyethylene glycol.

Fusion may be restricted to cytoplasm or nuclei may fuse as well. A cell formed by the fusion of dissimilar cells is often referred to as a heterokaryon.

(26 Mar 1998)