What is "nucleolus"

Nucleolus \Nu*cle"o*lus\, n.; pl. Nucleoli. [L., a little nut, dim. of nucleus.]

1. A little nucleus.

2. (Biol.) A small rounded body contained in the nucleus of a cell or a protozoan.

   Note: It was termed by Agassiz the entoblast. In the protozoa, where it may be situated on one side of the nucleus, it is sometimes called the endoplastule, and is supposed to be concerned in the male part of the reproductive process. See Nucleus.

1845, from Latin nucleolus, literally "a little nut," diminutive of nucleus (see nucleus).

n. (context cytology English) A conspicuous, rounded body within the nucleus of a cell.

1. n. a small round body of protein in a cell nucleus; nucleoli contain RNA and are involved in protein synthesis [syn: nucleole]

2. [also: nucleoli (pl)]

The nucleolus ( or , plural nucleoli or ) is the largest structure in the nucleus of eukaryotic cells, where it primarily serves as the site of ribosome synthesis and assembly. Nucleoli also have other important functions like assembly of signal recognition particles and playing a role in the cell's response to stress. Nucleoli are made of proteins and RNA and form around specific chromosomal regions. Malfunction of nucleoli can be the cause of several human diseases.