Fig. 1.

Synaptophysin immunoreactivity in the dentate gyrus of ECL wild-type and ApoE-KO mice. C57BL/6J mice (A–C) and apoE-KO mice (D–F) showed different responses to estradiol after ECL. Two weeks after surgery, sham-OVX mice (A, WT; D, apoE-KO) showed less immunoreactivity in the middle molecular layer than in the inner or outer layer of the dentate gyrus. In wild-type C57BL/6J mice, OVX causes a decrease in both the relative thickness and OD of the inner layer (B), whereas estradiol replacement brought inner layer thickness and OD back to sham-OVX levels (C). In apoE-KO mice, OVX (E) and estradiol replacement (F) made no significant changes in inner molecular layer thickness or OD. Width of the outer molecular layer was also increased in the WT E₂-replaced mice (C). In apoE-KO mice, outer molecular layer width was unaffected by estrogen treatment (D–F).H, Hilus; G, granular layer;O, outer; M, middle; I, inner molecular layer.