Light and electron microscopic observations of an intranucleolar body in nerve cells

Abstract

An intranucleolar body, considered to be the equivalent of the “nucleololus” of the light microscopists, is described in light and electron microscopic preparations of nerve cells of the monkey (Macaca mulata) cerebellar cortex and in Englenu gracilis. It is distinct from other nucleolar of nuclear components both in its appearance and in its staining reactions. Electron micrographs show that it contains a compact meshwork of fine filaments and granules and that it has no limiting membrane. Cytochemical tests indicate that it contains neither DNA nor RNA although it stains readily for proteins and bound lipids. It is suggested that the “nucleololus” may be concerned in nucleolar protein synthesis.