Intrinsic brain tumors, those that originate from neural cells within the brain and spinal cord, occur more frequently in older adults and children than they do in the general population. The main feature that makes intrinsic brain tumors different from cancers arising from other organs in the body is the fact that they rarely, if ever, metastasize outside the brain. Some cells in brain tumors do, however, stop dividing long enough to migrate a few millimeters away from the parent tumor to form new intracranial tumors. The most malignant of these is called glioblastoma multiforme (GBM).
In men and women less than 20 years old, brain cancer is, after leukemia, the next most prevalent cause of cancer deaths. Apart from leukemia, intracranial-derived tumors are the next leading cause of fatality in men between the ages of 20 and 30. In females between 20 and 39 years old, brain tumors are the fifth most prevalent cause of cancer deaths.
Luckily, GBM is infrequent; there are no more than two or three new cases per 100,000 individuals and account for only 20% of all intracranial neoplasms. Their propensity to invade the surrounding brain tissue means that it is not possible for them to be completely eradicated by surgical means. Try scraping off every bit of butter from a slice of toast.
GBM arises from cells in the brain called glial cells. Neurons, which are generally post-mitotic, meaning they lose the ability to divide once they have achieved terminal differentiation. Glial cells, on the other hand, may continue to divide and replicate throughout life. There is evidence from in vivo and in vitro studies to suggest that some, if not all, astrocytomas arise in utero.
The human brain is home to three types of glial cells: oligodendrocytes, astrocytes and microglial cells. The most numerous of these are the astrocytes, star-shaped cells. These cells give rise to tumors called astrocytomas, the most malignant of which are the GBM. The median survival time in GBM is less than five months if left untreated.
Astrocytes are characterized by their starry morphology and the presence of glial fibrillary acidic protein (GFAP). The normal function of astrocytes is to supply nutrients to nerve cells, support the vascular cells that comprise the blood brain barrier and repair damaged cells following trauma. New studies suggest that they communicate with neuronal cells by secreting glutamate, the brain's main excitatory neurotransmitter.
Other glial cells include the oligodendrocytes. These have fewer 'arms' than do astrocytes. The primary function of the oligodendrocytes is to form the myelin sheath that insulates nerve cells and accelerates the rate of neural transmission. One oligodendrocyte can insulate up to 50 separate neuronal cells. The myelin sheath is subject to attack by the immune system in the chronic and debilitation condition, multiple sclerosis (MS).
Microglia are the smallest members of the glial cell team. Their main function is to provide a rapid response to invading foreign bodies and prepare them for slaughter by T-cells. They do this by engulfing foreign matter in a process called phagocytosis. Resting microglia are the prettiest, and look like tiny astrocytes. Activated microglial cells look more bulbous with the processes less prominent.
In men and women less than 20 years old, brain cancer is, after leukemia, the next most prevalent cause of cancer deaths. Apart from leukemia, intracranial-derived tumors are the next leading cause of fatality in men between the ages of 20 and 30. In females between 20 and 39 years old, brain tumors are the fifth most prevalent cause of cancer deaths.
Luckily, GBM is infrequent; there are no more than two or three new cases per 100,000 individuals and account for only 20% of all intracranial neoplasms. Their propensity to invade the surrounding brain tissue means that it is not possible for them to be completely eradicated by surgical means. Try scraping off every bit of butter from a slice of toast.
GBM arises from cells in the brain called glial cells. Neurons, which are generally post-mitotic, meaning they lose the ability to divide once they have achieved terminal differentiation. Glial cells, on the other hand, may continue to divide and replicate throughout life. There is evidence from in vivo and in vitro studies to suggest that some, if not all, astrocytomas arise in utero.
The human brain is home to three types of glial cells: oligodendrocytes, astrocytes and microglial cells. The most numerous of these are the astrocytes, star-shaped cells. These cells give rise to tumors called astrocytomas, the most malignant of which are the GBM. The median survival time in GBM is less than five months if left untreated.
Astrocytes are characterized by their starry morphology and the presence of glial fibrillary acidic protein (GFAP). The normal function of astrocytes is to supply nutrients to nerve cells, support the vascular cells that comprise the blood brain barrier and repair damaged cells following trauma. New studies suggest that they communicate with neuronal cells by secreting glutamate, the brain's main excitatory neurotransmitter.
Other glial cells include the oligodendrocytes. These have fewer 'arms' than do astrocytes. The primary function of the oligodendrocytes is to form the myelin sheath that insulates nerve cells and accelerates the rate of neural transmission. One oligodendrocyte can insulate up to 50 separate neuronal cells. The myelin sheath is subject to attack by the immune system in the chronic and debilitation condition, multiple sclerosis (MS).
Microglia are the smallest members of the glial cell team. Their main function is to provide a rapid response to invading foreign bodies and prepare them for slaughter by T-cells. They do this by engulfing foreign matter in a process called phagocytosis. Resting microglia are the prettiest, and look like tiny astrocytes. Activated microglial cells look more bulbous with the processes less prominent.
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