During which stage of nuclear division do chromosomes move to opposite poles of the cell?

During anaphase, the key event is the separation of sister chromatids, which are pulled apart toward opposite poles of the cell. This process begins when the centromeres that hold the sister chromatids together split, allowing the microtubules of the spindle apparatus to attach to the kinetochores of each chromatid. The spindle fibers shorten, dragging the chromatids toward opposite ends of the cell, ensuring that each new daughter cell will receive an identical set of chromosomes.

In contrast, in metaphase, chromosomes are aligned at the cell's equatorial plane, but they do not move to the poles just yet. During telophase, the chromosomes have already reached the opposite poles and begin to de-condense back into chromatin, and a nuclear envelope re-forms around each set of chromosomes. In prophase, the chromosomes begin to condense and become visible, but they have not yet moved to the poles of the cell. Thus, anaphase is the distinct phase where the critical movement of chromosomes toward opposite directions occurs.