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).
Brain tumors are the second most common cause of cancer deaths in males and females under the age of 20. After leukemia, intrinsic brain tumors are the second leading cause of cancer deaths in men between the ages of 20 and 29. They are the fifth most frequent cause of cancer deaths among females between the ages of 20 and 39.
GBM is rare, with only two or three new cases per 100,000 population. They account for one-fifth of all tumors inside the cranium. Because of GBM cells' ability to break away from the main tumor, migrate a few millimeters within the brain and start dividing again to form new tumors, they are impossible to completely eradicate by surgery. It's is like trying to remove all the 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, situated in the brain and spinal cord, have several important functions. Among these is providing support to the vascular cells that make up the blood brain barrier, providing nutrients to neuronal tissue and repairing damage caused by CNS trauma. Recent experiments indicate that one way that astrocytes communicate with nerve cells is by releasing glutamate, an excitatory neurotransmitter.
Oligodendrocytes have fewer spiny processes than astrocytes. Their main function is to produce the myelin sheath that surrounds nerve cell axons to insulate them and speed up nerve impulse transmission. A single oligodendrocyte can service as many as 50 different nerve cells. It is the myelin sheath that is attacked by the immune system in the autoimmune condition known as 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.
Brain tumors are the second most common cause of cancer deaths in males and females under the age of 20. After leukemia, intrinsic brain tumors are the second leading cause of cancer deaths in men between the ages of 20 and 29. They are the fifth most frequent cause of cancer deaths among females between the ages of 20 and 39.
GBM is rare, with only two or three new cases per 100,000 population. They account for one-fifth of all tumors inside the cranium. Because of GBM cells' ability to break away from the main tumor, migrate a few millimeters within the brain and start dividing again to form new tumors, they are impossible to completely eradicate by surgery. It's is like trying to remove all the 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, situated in the brain and spinal cord, have several important functions. Among these is providing support to the vascular cells that make up the blood brain barrier, providing nutrients to neuronal tissue and repairing damage caused by CNS trauma. Recent experiments indicate that one way that astrocytes communicate with nerve cells is by releasing glutamate, an excitatory neurotransmitter.
Oligodendrocytes have fewer spiny processes than astrocytes. Their main function is to produce the myelin sheath that surrounds nerve cell axons to insulate them and speed up nerve impulse transmission. A single oligodendrocyte can service as many as 50 different nerve cells. It is the myelin sheath that is attacked by the immune system in the autoimmune condition known as 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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