Telophase (from the Greek τελος meaning "end") is a reversal of prophase and prometaphase events. It "cleans up" the after effects of mitosis.
At telophase, the nonkinetochore microtubules continue to lengthen, elongating the cell even more. Corresponding sister chromosomes attach at opposite ends of the cell.
A new nuclear envelope, using fragments of the parent cell's nuclear membrane, forms around each set of separated sister chromosomes.
Both sets of chromosomes, now surrounded by new nuclei, unfold back into chromatin. Mitosis is complete, but cell division is not yet complete.