Final answer:
Brain cancers are mostly comprised of neuroglia because neuroglial cells have a higher division rate and are exposed to various factors that could increase the risk of mutations leading to cancer, unlike neurons which are post-mitotic.
Step-by-step explanation:
Reasons Why Brain Cancers Are Comprised of Neuroglia
Rapidly growing brain cancers, such as gliomas, are often composed of neuroglial cells rather than neurons for several reasons. First, neuroglial cells divide and regenerate more readily compared to neurons, which are mostly terminally differentiated and do not divide after maturity. This higher mitotic activity in glial cells makes them more susceptible to mutations that can lead to cancer. Second, glial cells provide support and maintenance functions critical to neurons' survival, such as ion buffering, nutrient transport, and myelin sheath formation. Their important role in the brain's homeostasis and protective functions—like forming the blood-brain barrier—may expose them to various factors that could increase the risk of mutations leading to cancer.