Final answer:
The spindle apparatus is broken down during telophase, the final stage of mitosis and meiosis, where chromosomes decondense, nuclear envelopes reform, and spindle microtubules are depolymerized.
Step-by-step explanation:
The spindle apparatus is a crucial structure for the process of cell division in both mitosis and meiosis. Its main function is to ensure that chromosomes are accurately segregated into the daughter cells. The spindle apparatus is dismantled during telophase, which is the final stage of both mitosis and meiosis.
During telophase, the chromosomes that have been separated reach the opposite poles of the cell, begin to decondense back into a less tightly coiled chromatin state, and the nuclear envelopes start to reform around each set of chromosomes.
The spindle's microtubules are depolymerized into tubulin monomers, which will be reused to assemble new cytoskeletal components for the daughter cells. After this breakdown of the spindle apparatus, the cell progresses to cytokinesis, where the cytoplasm divides, completing the process of cell division.