Electron micrograph of ubiquitin‐positive intraneuronal inclusions in the extra‐motor cortices in patients with amyotrophic lateral sclerosis

The ultrastructure of ubiquitin‐positive intraneuronal inclusions in extra‐motor cortices was examined in two patients with amyotrophic lateral sclerosis associated with dementia (ALS‐D) using paired routine electron microscopic ultrathin sections and adjacent 1 μm thick semithin sections. The ubiquitin‐positive structures consisted mainly of granules associated with a few filaments of approximately 15 nm in diameter. The granules seemed to consist of altered ribosomes, namely they were less electron dense and more irregular and had more amorphous outlines than did the ribosomes in non‐ubiquitinated cytoplasms. Our findings suggest the development of ribosome‐associated and ubiquitin‐related abnnormalities in the neurons of the extra‐motor cortices of ALS‐D patients.