Dorsal view of the forebrain of a wild-type zebrafish embryo

Despite our apparent perfect bilateral symmetric body plan, we all show small but conspicuous left-right asymmetries that are thought to be evolutionarily advantageous. Brain lateralisation, for instance, leads to an increase in cognitive performance. Zebrafish are particularly useful models to study how left-right brain asymmetries arise during embryonic development and how the resultant asymmetric neuronal circuitry ultimately impacts on function and behaviour. This figure is a monochrome composite of a confocal micrograph showing the dorsal view of the forebrain of a wild-type zebrafish embryo at 4 days post-fertilization. Wild-type specimens display noticeable neuroanatomical asymmetries of the habenular nuclei in the forebrain, which can be visualised with the help of antibodies labelling different structures. Here the arrangement of the axons, synaptic neuropil and a subtype of habenular neurons are predominantly enriched in the left side of the brain. Width of image is approximately 275 micrometres.