noun, plural: nucleoli
Nucleolus is a round and granular organelle located inside the nucleus. It is composed of proteins, DNA, and RNA. In higher eukaryotes, three major regions are distinct: the fibrillar center, the dense fibrillar component, and the granular component.1 In plants, another structure is recognizable. This is called the nucleolar vacuole, a clear area in the center of the nucleolus.2
Word origin: Latin, diminutive of nucleus (kernel)
- nucleolar organizing region
- Nucleolar organizer region banding
- Nucleolar protein 3
- nucleolar (adjective, of, or relating to, nucleolus)
1 Koberna, K., Malínský, J., Pliss, A., Mašata, M., Večeřová, J., Fialová, M., Bednár, J., and Raška, I. (2002). "Ribosomal genes in focus: new transcripts label the dense fibrillar components and form clusters indicative of "Christmas trees" in situ". J. Cell Biol. 157 (5): 743–8.
2 Beven, A. F., Lee, R., Razaz, M., Leader, D. J., Brown, J. W., and Shaw, P. J. (1996). "The organization of ribosomal RNA processing correlates with the distribution of nucleolar snRNAs". J. Cell. Sci. 109 (6): 1241–51.