Coloured transmission electron micrograph (TEM) of neurons (nerve cells) from the medial nucleus of the trapezoid body in the brainstem, part of the brains auditory (hearing) pathway. Neuronal cell bodies are orange, cell nuclei are red and synaptic boutons are blue. Boutons are presynaptic areas responsible for neurotransmitter storage and release. The auditory brain stem and possess some of the largest synaptic connections in the brain. The scale bar is equal to 5 micrometres.