Axon initial segments of the granule cell in the rat dentate gyrus: synaptic contacts on bundles of axon initial segments.

In Golgi and electron microscopic studies, dentate granule cell axon initial segments were revealed to be fasciculated in the granule cell layer and to receive many synapses. Combined Golgi-EM studies indicated that the presynaptic elements of these synapses might be beaded string-like axon collaterals of some type of basket cell.