The site of ribosomal RNA
(rRNA) synthesis in eukaryotic cells.
The nucleolus is dense, spherical in shape, and made up principally of rRNA
that is in the process of being transcribed
from rRNA genes. It lies within the cell nucleus
and is surrounded by the nuclear membrane. During cell
division the nucleolus disappears.
|The nucleolus is the dark circle within the larger
mottled circle of the nucleus