Metaphase arrest is caused by : a) Griseofulvin b) Vincristine c) Paclitaxel d) Colchicine e) Etoposide
**Core Concept**
Metaphase arrest refers to the condition where cells are halted in the metaphase stage of cell division, preventing the separation of chromosomes and the progression of the cell cycle. This phenomenon is crucial in cancer chemotherapy, where certain agents induce metaphase arrest to inhibit tumor growth.
**Why the Correct Answer is Right**
Paclitaxel (option C) induces metaphase arrest by stabilizing microtubules, which are essential for the separation of chromosomes during mitosis. By preventing microtubule disassembly, paclitaxel causes the cell cycle to pause at metaphase. This mechanism is distinct from other agents that induce metaphase arrest by disrupting microtubule formation, such as vinca alkaloids (e.g., vincristine).
**Why Each Wrong Option is Incorrect**
* **Option A:** Griseofulvin is an antifungal agent that inhibits microtubule assembly, but it does not induce metaphase arrest. Instead, it prevents the formation of new microtubules, which can lead to impaired cell division.
* **Option B:** Vincristine is a vinca alkaloid that inhibits microtubule formation by binding to tubulin. While it does cause metaphase arrest, its mechanism is different from that of paclitaxel, which stabilizes existing microtubules.
* **Option D:** Colchicine is another agent that inhibits microtubule formation by binding to tubulin. It is used to treat gout and prevent cell division in certain medical conditions, but it does not induce metaphase arrest in the same way as paclitaxel.
* **Option E:** Etoposide is a topoisomerase inhibitor that prevents DNA replication by inhibiting the enzyme topoisomerase II. While it is used in cancer chemotherapy, it does not induce metaphase arrest.
**Clinical Pearl / High-Yield Fact**
Paclitaxel and other microtubule-stabilizing agents can cause peripheral neuropathy as a side effect due to their effect on microtubules in neurons.
**Correct Answer:** C. Paclitaxel