The term pyramidal cell layer of the hippocampus is a cytoarchitectural term denoting the layer of the CA fields in which pyramidal cells are predominant. Its location is superficial to the oriens layer of the hippocampus; it is deep to the stratum radiatum of the CA fields in the CA1 field, CA2 field and deep to the stratum lucidum of the CA3 field ( Stephan-1975 ).