Synaptic contacts between mitral/tufted cells and GABAergic neurons containing calcium-binding protein parvalbumin in the rat olfactory bulb, with special reference to reciprocal synapses between them.

It has been believed so far that in the mammalian olfactory bulb, only granule cells form reciprocal synapses with mitral/tufted cells in the external plexiform layer (EPL). However, the present electron microscopic study demonstrated for the first time that another group of immunocytochemically defined interneurons different from granule cells, viz., neurons containing a specific calcium-binding protein parvalbumin, also made reciprocal synapses with mitral/tufted cells in the EPL.