Activity of acid phosphatase and TPP-ase at a fine structure level in the neuroglia as related to myelination of the brain.

An ultrastructural investigation of the activity of acP and TPP-ase in the neuroglia of different developmental stages of the rabbit corpus callosum was performed. The observations made, lead to following conclusions: 1. The strongest demonstration of end products of acP activity was observed in the large dense bodies of oligodendrocytes at the culminating period of myelination gliosis. 2. At the peak of myelinogenesis a rise in the TPP-ase activity in the oligodendrocytes was localized mainly in the Golgi apparatus. However even in this period the Golgi system was only partially filled with reaction precipitates. 3. The increase of lysosomal acid phosphatase and of TPP-ase activity of the Golgi system of oligodendrocytes seems to be connected with the metabolic processes leading to deposition of myelin components.