Tumours of Nervous Tissue
1. Precursors of neural cells can give rise to medulloblastomas. Once mature neurons are formed they lose the power of mitosis and do not give origin to tumours. Certain tumours called germinomas appear near the midline mostly near the third ventricle. They arise from germ cells that also give rise to teratomas.
2. Most tumours of the brain arise from neuroglial cells. Astrocytomas are most common. Oligodendromas are also frequent.
3. Tumours can also arise from ependyma and from Schwann cells.