The new nuclear membrane develops during the telophase of cell division.
During telophase, which is the final stage of mitosis, the chromosomes that were separated during anaphase reach the opposite poles of the cell. As these chromosomes de-condense back into chromatin, the nuclear envelope reforms around each set of chromosomes, creating two distinct nuclei within the cell. This reformation of the nuclear membrane is critical because it restores the nucleus’s integrity and prepares the cell for the next interphase, where it will carry out its regular functions and prepare for another round of cell division.