An electron microscope study on the termination of the perforant path fibres in the hippocampus and the fascia dentata

Summary Morphology and distribution of the perforant path fibres in the hippocampus and the fascia dentata of the rat have been studied in the electron microscope. Investigations were carried out on normal tissue as well as on tissue degenerating after entorhinal damage. The perforant path fibres were relatively thin and the terminals small. Two terminal fields were found to be of quantitative importance, one in the middle third of stratum moleculare of the fascia dentata, the other in stratum lacunosum moleculare of regio inferior of the hippocampus. Some of the observations have been expressed in numerical terms.This study was supported in part by Grant NB 02215 from the National Institute of Neurological Diseases and Blindness, U.S. Public Health Service.