Retina. Coloured light micrograph of a section through a retina. The eye works by allowing light to be focused by the lens onto the retina. The retina contains specialised light sensitive photoreceptor cells (orange and pink, top) used to distinguish between colours (cone cells) and to see at night (rod cells). The light is relayed as electrical signals through sensory nerve cells, called bipolar cells (pink, centre). The two yellow layers above and below the bipolar nerve cells are synaptic layers, where the dendrites and axons (fibrous extensions) of the photoreceptors and neurons pass on the signals to others below them. The lowest layer (pink) is made up of ganglion nerve cells which pass the signals to the brain. Magnification: x120 when printed 10cm tall.