Light and electron microscopic observations on the relationship between Hirano bodies, neuron and glial perikarya in the human hippocampus.

Hippocampi from two intellectually normal and four demented subjects were examined in autopsy material. Large Hirano bodies seen by light and electron microscopy were thought to be glial in origin and not to be produced by the perikarya of neurons as has been suggested in the literature. Myelination of two Hirano bodies found in the stratum lacunosum-granulosum where neuron perikarya are rare suggests that these bodies are produced by oligodendroglia. Hirano bodies were found to be associated with neurons showing granulovaculoar degeneration. With electron microscope they were frequently seen to be divided by clefts filled with amorphous material which possibly consisted of free ribosomes.