Excitatory synapse CNS, TEM

Excitatory synapse from the human central nervous system, transmission electron micrograph (TEM). Note the synaptic zone, synaptic vesicles and single dark dense core vesicle. Chemical synapses are specialized junctions through which nerve cells signal one another or other non-neuronal cells such as muscles. At a typical synapse an axon and a dendrite flank each other across a slender gap (synaptic cleft). Signalling molecules, known as neurotransmitters, are contained in tiny vesicles of the axon. Neurotransmitters pass rapidly from axon to dendrite triggering an electrical impulse. Neurons are (also known as nerve cells) are cells of the nervous system that are specialized to carry messages through an electrochemical process. Magnification: x3,600 when shortest axis printed at 25 millimetres.