 The stratum pyramidale is the third deepest hippocampal layer, and in relation to the stratum lucidum, is located underneath it.The stratum pyramidale houses cell bodies of the pyramidal neurons, which are the foundational excitatory neurons of the hippocampus.In the CA3 region of the hippocampus, the stratum pyramidale connects with the stratum lucidum by mossy fibers that run through both subfields.