Oligodendrogliomas: oligodendrocytes
Brainstem glioma: develop in the brain stem
Optic nerve glioma: develop in or around the optic nerve
Mixed gliomas, such as oligoastrocytomas, contain cells from different types of glia

By grade
Gliomas are further categorized according to their grade, which is determined by pathologic evaluation of the tumor. The neuropathological evaluation and diagnostics of brain tumor specimens is performed according to WHO Classification of Tumours of the Central Nervous System. Biologically benign gliomas [WHO grade I] are comparatively low risk and can be removed surgically depending on their location 
Low-grade gliomas [WHO grade II] are well-differentiated (not anaplastic);  these tend to exhibit  benign tendencies and portend a better prognosis for the patient. However, they have a uniform rate of recurrence and increase in grade over time so should be classified as malignant. High-grade [WHO grades III–IV] gliomas are undifferentiated or anaplastic; these are malignant and carry a worse prognosis.Of numerous grading systems in use, the most common is the World Health Organization (WHO) grading system for astrocytoma, under which tumors are graded from I (least advanced disease—best prognosis) to IV (most advanced disease—worst prognosis). By location
Gliomas can be classified according to whether they are above or below a membrane in the brain called the tentorium. The tentorium separates the cerebrum (above) from the cerebellum (below). The supratentorial is above the tentorium, in the cerebrum, and mostly found in adults (70%). The infratentorial is below the tentorium, in the cerebellum, and mostly found in children (70%). The pontine tumors are located in the pons of the brainstem.
Serious illness has followed ingestion of 7.5 g (0.26 oz). The mean lethal oral dose for an adult is estimated at 45 g (1.6 oz).The anesthetic use of chloroform has been discontinued because it caused deaths due to respiratory failure and cardiac arrhythmias. Following chloroform-induced anesthesia, some patients suffered nausea, vomiting, hyperthermia, jaundice, and coma due to hepatic dysfunction. At autopsy, liver necrosis and degeneration have been observed.Chloroform has induced liver tumors in mice and kidney tumors in mice and rats. The hepatotoxicity and nephrotoxicity of chloroform is thought to be due largely to phosgene. Conversion to phosgene
Chloroform converts slowly in air to the extremely poisonous phosgene (COCl2), releasing HCl in the process. 2 CHCl3 + O2 → 2 COCl2 + 2 HClTo prevent accidents, commercial chloroform is stabilized with ethanol or amylene, but samples that have been recovered or dried no longer contain any stabilizer. Amylene has been found ineffective, and the phosgene can affect analytes in samples, lipids, and nucleic acids dissolved in or extracted with chloroform. Phosgene and HCl can be removed from chloroform by washing with saturated aqueous carbonate solutions, such as sodium bicarbonate. This procedure is simple and results in harmless products. Phosgene reacts with water to form carbon dioxide and HCl, and the carbonate salt neutralizes the resulting acid.Suspected samples can be tested for phosgene using filter paper (treated with 5% diphenylamine, 5% dimethylaminobenzaldehyde in ethanol, and then dried), which turns yellow in phosgene vapor.