In the nematodeCaenorhabditis elegans, 300 of the 959 somatic nuclei present in the adult hermaphrodite are located in syncytia. These syncytia are formed by the fusion of mononucle-ate cells throughout embryonic and postembryonic development. These cell fusions occur in a well-characterized stereotypical pattern, allowing investigators to study many cell fusion events at the molecular and cellular levels. Using tools that allow visualization of cell membranes, cell junctions, and cell cytoplasm during fusion, genetic screens have identified manyC. eleganscell fusion genes, including those that regulate the fusion cell fate decision and two genes that encode components of the cell fusion machinery.
