Central nervous system, Zebrafish embryo

False-coloured SEM showing the early tissue architecture of the central nervous system (CNS) of a zebrafish (Danio rerio) embryo 24 hours post fertilisation. Brain (yellow), eye (blue), and lens (pale blue) tissue are highlighted. This image was acquired as part of research into the cellular and genetic mechanisms underlying the initial steps of brain development, a process called neurulation. Zebrafish embryos are used a model organism to understand how key genes regulate the three-dimensional organisation of cells in for example the central nervous system.