NEWS AND VIEWS 27 May 2026 A fertilized egg’s first few divisions rely on proteins stored in fibrous structures. The ordered nature of these structures and clues about their function are revealed. By Matthias Geyer Matthias Geyer is at the Institute of Structural Biology, the University of Bonn, Bonn 53127, Germany. Gregor Hagelueken Gregor Hagelueken is at the Institute of Structural Biology, the University of Bonn, Bonn 53127, Germany. Before an embryo can use its own genes, it relies on materials that have been packed into the egg. This is a precarious phase. In mammals, the fertilized egg divides several times before activating its own genome, meaning that early development depends almost entirely on preloaded proteins and RNA molecules. Many of these materials do not float freely inside the cell but are instead held by lattice-like structures that can be seen using an electron microscope.…