Chromosomal  doubling  can  occur  if a cell fails to divide after DNA
   replication.

   This  can  be  simulated  experimentally by applying colchicine, which
   interferes   with  spindle  formation,  to  somatic  cells  undergoing
   mitosis.  This  prevents  replicated  chromosomes  from  migrating  to
   opposite poles at anaphase.

   When   colchicine   is   removed,  the  tetraploid  cell  can  reenter
   interphase.