[TA] four layers formed by cells and cell processes; they are, beginning at the alveus and ventricular surface: the oriens layer [TA] (stratum oriens [TA]), which contains basal dendrites and axon collaterals of the pyramidal cells; the pyramidal layer [TA] (stratum pyramidale [TA]), which contains the somata of the large pyramidal cells of the hippocampus; the radiant layer [TA] (stratum radiatum [TA]), which contains the branching dendrites of the pyramidal cells and recurrent axon collaterals of the pyramidal cells; and the lacunar-molecular layer [TA] (stratum moleculare et substratum lacunosum [TA]), which contains the distal dendrites and some of the incoming axons of the preforant pathway. SYN: strata hippocampi [TA].