Metachromatic Leukodystrophy, an Electron Microscopic Study*†

Abstract

The study of 2 cases of metachromatic leukodystrophy disclosed a variety of alterations in the brain. Some were nonspecific, such as myelin breakdown, fibrillary gliosis, and enlargement of extracellular spaces. Glial metachromatic inclusions are characteristic of the disease. Their electronmicroscopic appearance resulted from 1. a variable combination of a lamellar pattern formed by a 58 to 56 Ā periodic alternation of osmiophilic dark and light bands, 2. partitions delimiting prismatic spaces within the inclusions, and 3. a nonosmiophilic matrix showing a strong affinity for PTA. The molecular and chemical significance of these inclusions is discussed.