Cerebrum
The cellular structure of the cerebrum is composed primarily of neurons and their support cells, which are broadly termed glial cells.
The 3 principal types of glial cells are astrocytes, oligodendrocytes, and microglia.
The glial cells provide supportive and regulatory functions for neurons, and in fact glial cells outnumber neurons.
These glial cells can give rise to glial tumors, such as astrocytomas, oligodendrogliomas, and glioblastomas, which are among the most common primary brain tumors.
Microglia have a function in the brain similar to that of the immune system.
Astrocytes play a role in creating the blood-brain barrier, which allows certain substances to selectively pass from the capillary system.
They are also responsible for reactive scar formation in the brain. Oligodendrocytes form myelin, which serves to electrically insulate the axons of nerve cells, allowing increased rates of conduction.
Abnormal proliferation of oligodendrocytes and astrocytes can lead to primary brain tumors called oligodendrogliomas and astrocytomas.
The cerebrum is composed of the telencephalon and the diencephalon.