Anaphase

This  phase is of shortest duration. It  begins  with  a sudden  separation  of the two chromatids of each   due  to splitting   of its centromere and  then a slow movement of  separted  chromatids  towards  opposite  poles  of mitotic   spindle . Factors responsible for splitting of centromeres and movement  of attachment  fibres, or  the fibres gradually  shorten,  pulling the chromatids towards   the  poles. Shortening of these  fibres may be due to their  contraction (due  to the  presence of contractile actin  proteinin these ) or  their  gradual depolymeriaztion  at polar  ends Simultaneously, however  the continuous spindle fibres somewhat  elongate, pushing the  spindle  poles more apart. Towards  the end of anaphase  when polar migration  of chromatids is complete , these  is a full  chromosomal  complement  at each  pole identical to the original karyotype  of parent cell. Soon, a nuclear envelope forms around each polar group, presumably from the endoplasmic reticulum.