In order to evaluate whether decreased neuronal density contributes to volumetric hippocampal atrophy, we performed the immunofluorescence staining of CA mature (NeuN+) pyramidal neurons and immature (DCX+PSA-NCAM+) neurons in the DG (sub)granular layer (N = 5 per group; 13–15 weeks of age). The gene discussed is NCAM1; the disease is hippocampal atrophy.