abnormal dentate gyrus morphology abnormal hippocampus region morphology abnormal hippocampus CA4 region morphology MP:0008269 MPheno.ontology abnormal dentate gyrus hilus morphology abnormal field CA4 of hippocampal formation abnormal hilus of dentate gyrus morphology any structural anomaly of the region of the hippocampal formation that is comprised of mossy cells that primarily receive inputs from granule cells in the dentate gyrus in the form of mossy fibers and from pyramidal cells in CA3, and send outputs into the dentate gyrus