Metachromatic bodies in the brain.

The purpose of this paper is to report the results of a study of the mucin, or mucin-like metachromatic substance, sometimes found in the white matter of the brain. This substance, occurring in small masses, has been referred to as " mucocytes." During the course of work on " grass sickness " in horses, these masses have been found; it therefore has become urgent, before continuing this investigation, to determine whether these metachromatic, masses or bodies are mere artefacts; and if they are not artefacts, whether they are pathological or normal str;ures, and what their origin and nature may be. The term " mucocytes"is that most commonly used, but it may be misleadingly derivative, and will not be used here. Varying descriptions of this mucin-like substance have been given, and different views of its origin and significance expressed. It has generally been reported as occurring in the form of multilobulated grape-like areas throughout the white matter. Metachromatic bodies have been described by different workers as occurring in normal brains and in a large variety of pathological material, including senile dementia, epidemic encephalitis, Wilson's disease, paralysis agitans, and Schilder's disease. Different views as to the origin and significance have been expressed. The views on their origin which have been put forward fall roughly into two groups: first, it has been suggested that the metachromatic bodies are pathological, either of cellular origin or of extracellular origin; secondly, that the metachromatic bodies are artefacts. The -literature contains references to the works of many authors who hold the opinion that metachromatic bodies are pathological and arise from cells. Grynifeltt (1923) found microscopical multilQbate patches in the white matter of the central nervous system of patients with senile dementia, paralysis agitans, and Wilson's disease. Working in association with P6lissier and Pages (1924), he also found these patches in dogs poisoned with