The effect of saponification on the mucopolysaccharides of the ground substance of the human brain: the relation to focal edema and multiple sclerosis.

The acid mucopolysaccharides of brain tissues are disclosed by their metachromatic staining with toluidine blue following saponification with potassium hydroxide, presumably as a result of the liberation of acid groups previously esterified. Earlier histochemical studies had disclosed the presence of neutral mucopolysaccharides by staining with the periodic acid-Schiff technique, and such staining is intensified by prior saponification. Many biochemical studies have reported the presence of both acid and neutral mucopolysaccharides in brain tissues. Within the white matter following brain edema, the quantity of stained mucopolysaccharides is decreased in the plaques of multiple sclerosis and pontine myelinolysis, and in the lesions of diffuse sclerosis. All of these are characterized by myelin loss with relative preservation of axons. The known physiological effects of the mucopolysaccharides on the water content of normal tissues, and on the properties and diffusability of the increments of fluid that constitute edema, lead to the suggestion that edema may play a major role in the pathogenesis of the demyelinating diseases, including multiple sclerosis.