Final answer:
The spindle is broken down and replaced with a phragmoplast during telophase of mitosis in a plant cell. Telophase is the phase where the chromosomes reach the opposite poles of the cell and the nuclear envelope starts to form around them.
Step-by-step explanation:
The spindle is broken down and replaced with a phragmoplast during telophase of mitosis in a plant cell. In telophas the chromosomes reach the opposite poles of the cell and the nuclear envelope starts to form around them. The mitotic spindle, which is responsible for separating the chromosomes, breaks down and is replaced by a structure called a phragmoplast, which helps in the formation of the new cell wall during cytokinesis.