The term layers of CA2 field refers to five cyto- and myeloarchitecturally defined substructures of the CA2 field of the CA fields. Beginning at their boundary with the white matter of the temporal lobe they are the alveus of the CA2 field, the stratum oriens of the CA2 field, the stratum pyramidale of the CA2 field, the stratum radiatum of the CA2 field and the stratum lacunosum moleculare of the CA2 field ( Bakst-1984 ).