Confocal micrograph showing the connections of the visual system in a four-day-old zebrafish embryo. Staining of the neurons, glia and optic nerve illustrate the connections between the retina and the brain. The retina is a multi-layered structure of retinal neurons that processes light information in the eye. The ganglion cell layer is closest to the bulb of the eye moving out towards the layer that contains the light sensitive cells - the rods and cones - towards the back of the retina. Both the retinal ganglion cell layers and photoreceptor cell layers are shown in cyan. The glial cells are shown in purple. The optic nerve (cyan) transmits information from the eye to the brain. The point at which the optic nerves meet is known as the optic chiasm.