Final answer:
Vincristine and colchicines are chemotherapy drugs that bind to tubulin and interfere with microtubule assembly and disassembly, specifically targeting the mitotic structure called spindles. This disrupts cell division.
Step-by-step explanation:
Vincristine and colchicines are chemotherapy drugs that disrupt mitosis by binding to tubulin and interfering with microtubule assembly and disassembly. These drugs target the mitotic structure known as spindles, which are microtubular fibers formed with the help of tubulin. By inhibiting spindle formation, cell division is prevented.