hippocampus stratum radiatum

Within the layered architecture of the hippocampus, the stratum radiatum lies immediately above the pyramidal cell layer in fields CA2 and CA1, and superficial to the stratum lucidum in CA3. It is the suprapyramidal region that houses two of the principal intrahippocampal connections: CA3 to CA3 associational fibres, and the CA3 to CA1 Schaffer collaterals. The layer is therefore defined less by its cell bodies than by the axonal traffic passing through it, since the Schaffer collateral projection is the main route by which activity in CA3 reaches CA1. Its Latin designation, the radiate layer of the hippocampus, reflects the radiating course of the apical dendrites that cross it from the pyramidal cells below.