Distribution of various types of oligodendrocytes and cellular localisation of iron in the frontal cortex of the adult rat.

Oligodendrocytes, called oligodendroglia, are present in the white and grey substance of the CNS. They constitute a heterogeneous group, in which 3 types of these cells have been distinguished: those of light, medium and dark cytoplasm. They locate themselves at the neurones and blood vessels. The number of light oligodendrocytes decrease with age, while the number of dark oligodendrocytes increase. In histochemical studies the product of the reaction located itself in the body and processes, indicating the participation of these cells in the metabolism of iron.