Fig. 5.

Environmental enrichment decreases the number of dense-core vesicles (A) and increases the width of the synaptic cleft (C) in the polymorph cell layer of the dentate gyrus. The number of synapses/μm³ (B), presynaptic membrane length, postsynaptic density length, number of docked vesicles and number of vesicles in the vesicle pool were not affected by the differential housing conditions (D–G). The ultrastructure of the polymorph cell layer of the dentate gyrus was assessed in mice kept in standard environment (SE) or environmental enrichment (EE) for 5 weeks. *P < 0.05 vs. SE. The values represent means + SEM, A, E, and F: n = 4–5/group; B, D, and G: n = 5/group; C: n = 3–5/group.