Commissural fibers terminate on non-pyramidal neurons in the guinea pig hippocampus -- a combined Golgi/EM degeneration study.

The combined Golgi/EM method was applied to guinea pig hippocampi with acute anterograde degeneration of the commissural afferents in order to identify possible synaptic contacts between commissural terminals and non-pyramidal neurons. Degenerating, electron-dense terminals of commissural origin were found in synaptic contact with both perikarya and dendrites of two identified non-pyramidal neurons in regio superior, namely a basket cell and a bipolar neuron in stratum oriens. The observed connection may form the morphological basis for the physiologically observed feed-forward inhibition of the pyramidal cells.