Autoradiography of the olfactory-hippocampal pathway in the cat with special reference to the perforant path

The anatomical pathway from the prepyriform cortex to the hippocampus in the cat was traced autoradiographically by means of anterograde transport of [3H] leucine. A direct projection from the prepyriform cortex to the lateral entorhinal area was confirmed in the cat: the termination of these fibers was largely confined to the outer part of the molecular layer. From the lateral entorhinal area, the perforant path fibres terminate on the most distal parts of the dendrites of the hippocampal granule and pyramidal cells. However, differences between cat and rat were found with respect to the terminations in the CA1 area.