During which phase of mitosis do the nuclear envelopes and nucleoli reappear?

During telophase, the nuclear envelopes and nucleoli reappear as part of the process of restoring the nucleus at the end of mitosis. This phase occurs after the chromosomes have successfully separated and migrated to opposite poles of the cell. In telophase, two distinct nuclei start to form around the separated sets of chromosomes, which are now de-condensing, allowing for the structural integrity of the nucleus to be re-established.

This reformation of the nuclear envelope is crucial as it encapsulates the genetic material, restoring the nucleus's function and preparing the cell for its next phase, which is cytokinesis, where the cytoplasm divides. The presence of reformed nucleoli also signifies the return to an active state of transcription, necessary for the cell's normal functions following cell division.

Other phases of mitosis, such as prophase, metaphase, and anaphase, do not involve the reappearance of these structures; instead, they are characterized by events like chromatin condensation, alignment of chromosomes at the equatorial plane, and separation of sister chromatids, respectively.