Elastic ‘tethers’ connect separating anaphase chromosomes in a broad range of animal cells.

We describe the general occurrence in animal cells of elastic components (“tethers”) that connect individual chromosomes moving to opposite poles during anaphase. Tethers, originally described in crane-fly spermatocytes, produce force on chromosome arms opposite to the direction the anaphase chromosomes move. In crane-fly spermatocytes tethers function to coordinate movements between chromosomes. Their presence in a broad range of cells suggests that they may be important in coordinating movements between chromosomes to ensure normal segregation. Tethers are previously unrecognised force-producing components of general mitotic mechanisms and need to be accounted for in general models of mitosis in terms of forces on chromosomes and in terms of what their roles might be, possibly in coordinating chromosome movements during mitosis.