Terminal branches of the perforant path, by contrast, fill from the outset of the pathological process the outer two-thirds of the molecular layer, but they are probably not responsible for the transmission of AD-related tau seeds, inasmuch as the involvement of the granular cells is a late event that occurs only after the development of abnormally altered axonal terminals in the inner third of the molecular layer, i.e., following the appearance of involved CA4 mossy cells. Here, MAPT is linked to Alzheimer disease.