Final answer:
The net-like structure formed by the spindle fibers during mitosis is called the kinetochore microtubule network.
Step-by-step explanation:
The net-like structure formed by the spindle fibers is called the kinetochore microtubule network. These microtubules, which are part of the mitotic spindle, originate from centrioles and play a crucial role in arranging and pulling apart chromosomes during mitosis.