Within most types of eukaryotic CELL NUCLEUS, a distinct region, not delimited by a membrane, in which some species of rRNA (RNA, RIBOSOMAL) are synthesized and assembled into ribonucleoprotein subunits of ribosomes. In the nucleolus rRNA is transcribed from a nucleolar organizer, i.e., a group of tandemly repeated chromosomal genes which encode rRNA and which are transcribed by RNA polymerase I. (Singleton & Sainsbury, Dictionary of Microbiology & Molecular Biology, 2d ed)

Descriptor ID	D002466
MeSH Number(s)	A11.284.430.106.279.345.175
Concept/Terms	Cell Nucleolus Cell Nucleolus Plasmosome Plasmosomes Cell Nucleoli Nucleoli, Cell Nucleolus, Cell

Below are MeSH descriptors whose meaning is more general than "Cell Nucleolus".

Below are MeSH descriptors whose meaning is related to "Cell Nucleolus".

Below are MeSH descriptors whose meaning is more specific than "Cell Nucleolus".