Ultrastructural evidence of the nucleolus of Entamoeba histolytica

Abstract

Although cell structure of Entamoeba histolytica is well known, the presence of nucleolar material has not been described with the electron microscope. Here we use light and electron microscopy cytochemical techniques to search for evidence1 of nucleolar material in this amoeba trophozoyte. Toluidine blue for RNA and silver staining for nucleolar organizer stain peripheral intranuclear material2. With the electron microscope, a3 similar material is fibro-granular and is contrasted with techniques for ribonucleoproteins and nucleolar organizer, but it is negative for DNA. These results show ultrastructural evidence for the presence of a peripheral and ring-shaped nucleolus4 in the nucleus of E. histolytica. It is suggested that this intranuclear organelle is a general feature in eukaryotes.