Coloured transmission electron micrograph (TEM) of olfactory bulb neuropil. A large dendrite (blue) of a mitral cell with microtubules, mitochondria and endoplasmic reticulum cisterns is surrounded by small dendrites of granule cells (red). Reciprocal dendrodendritic synapses with synaptic vesicles on both sides can be seen between the two dendrites. Sheets of astrocytic processes (green) surround and isolate the synapses.