Figure 2.

Schematic illustration of nucleolar assembly at the end of mitosis. In telophase transcription of the rDNAs is activated (white octagons) in several NORs (nucleolar organizing regions), whereas the early and late nucleolar processing complexes are located in the prenucleolar bodies (PNBs), consequently the PNBs containing both the D and G processing complexes (respectively D: green and G: red) appeared as yellow structures. The assembly of the nuclear envelope around chromatin is not complete. In early-G₁ a, transcription and early processing take place and generate the DFC (D: green), the late processing complexes are in PNBs (red), and the nuclear envelope is assembled at the periphery of the nucleus (double black rings). In early-G₁ b, the late processing complexes are recruited around the DFC (D) forming the granular component (G: red) and the incipient nucleoli form a single nucleolus. In early-G₁ b, a few PNBs are still present and cytokinesis is not complete (not shown). In Hela cells the duration of the telophase is ≈ 10 min, early-G₁ a is ≈20 min and early-G₁ b is ≈90 min.