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 used in the present study to examine oligodendroglial cell changes and reactivity. The samples were processed for light and transmission electron microscopy. Four main types of oligodendrocyte populations have been found: resting or unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischaemic oligodendroglial cells and hyperthrophic phagocytic oligodendrocytes. The unreactive or resting oligodendrocyte type exhibited a fusiform or elongated shape, a clear or dense band of scarce perikaryal cytoplasm and a nucleus with peripheral heterororomatin masses. Clear or dense reactive oligodendrocytes showed increased amount of perikaryal citoplasm, dilated endoplasmic reticulum and nuclear envelope, numerous clear, oedematous mitochondria and dense bodies. These oligodendrocytes appeared associated with degenerated myelinated axons. Anoxic-ischaenmic oligodendrocytes showed lacunar enlargement of endoplasmic reticulum, dilated Golgi complex and enlargement and disassembly of nuclear envelope. They appeared also in contact with degenerated myelinated axons. Hypertrophic phagocytic oligodendrocytes were observed engulfing the associated degenerated myelinated axons, invading the myelin sheath, separating the myelin lamellae and exerting myelinolitic effects. Oligodendroglialpseudopodic expansions were observed phagocyting the axoplasmic matrix and leaving a huge vacuolar axoplasmic space. The vasogenic and cytotoxic components of traumatic brain oedema are discussed in relation with the oligodendroglial cell changes and reactivity.