Final answer:
Microtubules and actin filaments are critical mediators of cell division in the M phase. Microtubules help separate chromosomes, while actin filaments create a cleavage furrow during cytokinesis.
Step-by-step explanation:
The two filaments that are critical mediators of cell division in the M phase are microtubules and actin filaments. Microtubules form the spindle apparatus, which helps separate the duplicated chromosomes and ensure that each daughter cell receives the correct set of chromosomes. Actin filaments, along with myosin, create a cleavage furrow that eventually splits the cell in two during cytokinesis.