Ultrastructure of a polysome-lamellae complex in a human paraganglioma

Study of a human abdominal paraganglioma under electron microscopy revealed an unusual cytoplasmic inclusion appearing as a hollow cylinder made up of one or several concentric lamellae surrounded by single or aggregated granules. Cross sections of the lamellar element show a discontinuous juxtaposition of particles. It is moderately dense and is bordered by 140--to 250-A granules of sure ribosomal nature. The inclusion is closely connected to the rough endoplasmic reticulum. The origin and significance of this complex are discussed.