Oligodendroglial cell behaviour in traumatic oedematous human cerebral cortex: a light and electron microscopic study

Cortical biopsies of 12 patients with traumatic brain injuries have been us ed in the present study to examine oligodendroglial cell changes and reacti vity. The samples were processed for light and transmission electron micros copy. Four main types of oligodendrocyte populations have been found: resti ng or unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischae mic oligodendroglial cells and hyperthrophic phagocytic oligodendrocytes. T he unreactive or resting oligodendrocyte type exhibited a fusiform or elong ated shape, a clear or dense band of scarce perikaryal cytoplasm and a nucl eus with peripheral heterorocromatin masses. Clear or dense reactive oligod endrocytes showed increased amount of perikaryal citoplasm, dilated endopla smic reticulum and nuclear envelope, numerous clear, oedematous mitochondri a and dense bodies. These oligodendrocytes appeared associated with degener ated myelinated axons. Anoxic-ischaemic oligodendrocytes showed lacunar enl argement of endoplasmic reticulum, dilated Golgi complex and enlargement an d disassembly of nuclear envelope. They appeared also in contact with degen erated myelinated axons. Hypertrophic phagocytic oligodendrocytes were obse rved engulfing the associated degenerated myelinated axons, invading the my elin sheath, separating the myelin lamellae and exerting myelinolitic effec ts. Oligodendroglialpseudopodic expansions were observed phagocyting the ax oplasmic matrix and leaving a huge vacuolar axoplasmic space. The vasogenic and cytotoxic components of traumatic brain oedema are discussed in relati on with the oligodendroglial cell changes and reactivity.