Re-establishment of nuclei in mitosis Around which mitotic phase does a nuclear envelope form around each set of sister chromatids?

Introduction / Context:
A hallmark of mitotic exit is the reconstruction of fully functional nuclei. Mastering the timeline of mitotic events helps interpret micrographs and troubleshoot cell cycle experiments. This item asks when separate nuclear envelopes encapsulate segregated chromatids.

Given Data / Assumptions:

• Standard eukaryotic mitosis sequence.
• Chromatids have already separated by the time the envelope reforms.
• Chromosome decondensation accompanies nuclear re-formation.

Concept / Approach:
Microtubule attachments and motion occur while the nuclear envelope is disassembled (prometaphase through metaphase and anaphase). Once chromatids reach the poles, the cell rebuilds the envelope using ER-derived membranes and lamins, which is the defining feature of telophase, followed by cytokinesis.

Step-by-Step Solution:

Verification / Alternative check:
Live-cell imaging with fluorescent lamins or nuclear pore components shows recruitment to chromatid masses specifically in telophase.

Why Other Options Are Wrong:

• Anaphase: movement, not envelope re-formation.
• Metaphase: alignment on the plate with envelope absent.
• Prophase/prometaphase: envelope breakdown begins; opposite of re-formation.

Common Pitfalls:
Equating late anaphase with telophase; use the envelope reassembly as the telophase marker.

Final Answer:
Telophase