Synapse Nerve Junction, TEMBy Thomas Deerinck

Synapse. Coloured transmission electron micrograph (TEM) of a synapse, a junction between two nerve cells, in the brain. At a synapse an electrical signal is transmitted from one cell to the next in only one direction. The nerve cells are pink, with the pre-synaptic cell at left and the post-synaptic cell at right. Mitochondria, supplying the cells with energy, are yellow. When an electrical signal reaches a synapse it triggers the release of neurotransmitter chemicals from vesicles (red) at the end of the presynaptic cell. The neurotransmitters cross a microscopic gap and bind to receptors on the post- synaptic cell. Magnification: 50,000x when printed 10 centimetres across.