Upon activation of protein production and thus of ribosomal subunits assembly, cell nucleoli may fuse forming a large nucleolar network or nucleolonema. The network is constituted by very thick loose strands 100-200 nm in diameter. The nucleolonema maintains all the nucleolar components, although their localization is somewhat different. For example, the the granular component, which mostly contains more mature pre-ribosomal particles, is found not only around the nucleolonema but also along the periphery of the strands. The amorphous part and fibrous region are focused in the central parts of the strands. A large subunit takes about 1 hour to get mature. When operating intensively, the nucleolar synthesis produces a huge number of ribosomes that is equal to 1500-3000 per minute. A nucleolus may comprise about 10⁵ precursors of ribosomes.