experimental animal models resembling most human brain tumor types can be induced by exposure to oncogenic viruses or chemical carcinogens : astrocytomas and glioblastoma multiforme can be produced experimentally by intracerebral injection of oncornaviruses , whereas medulloblastomas , choroid plexus papillomas , and ependymomas can be induced by the papovaviruses .
C0004114
astrocytomas
C0017636
glioblastoma multiforme