Nucleolus and rRNA Gene Chromatin in Early Embryo Development

Trends Genet. 2019 Nov;35(11):868-879. doi: 10.1016/j.tig.2019.06.005. Epub 2019 Jul 18.


The nucleolus is the largest substructure in the nucleus and forms around the nucleolar organizer regions (NORs), which comprise hundreds of rRNA genes. Recent evidence highlights further functions of the nucleolus that go beyond ribosome biogenesis. Data indicate that the nucleolus acts as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we discuss recent findings that have revealed how nucleolar structure and rRNA gene chromatin states are regulated during early mammalian development and their contribution to the higher-order spatial organization of the genome.

Keywords: early development; genome architecture; heterochromatin; nucleolus; oocyte; rRNA genes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Cell Differentiation / genetics
  • Cell Nucleolus / genetics
  • Cell Nucleus
  • Chromatin / genetics*
  • Embryonic Development / genetics*
  • Embryonic Stem Cells / metabolism
  • Gametogenesis / genetics
  • Genes, rRNA*
  • Genome
  • Mammals
  • Oocytes / metabolism


  • Chromatin