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. 2023 Feb 10;33(3):133–149. doi: 10.1002/hipo.23509

FIGURE 2.

FIGURE 2

Mossy fiber (MF) boutons originating from rostrodorsal dentate gyrus (DG) appear to preferentially target intermediate CA2 over the neighboring, dorsal CA3 region. (a) Horizontal section from dorsal hippocampus, at dorsal injection site, showing GCaMP‐labeled CA2/CA3 pyramidal neurons (green) and mCherry‐labeled DGGCs (red). Inset: Lateral view of hippocampus depicting dorsal and intermediate depths for analysis of mossy fiber bouton (MFB) morphometrics. (b) Horizontal section from intermediate hippocampus exhibiting CA2‐specific innervation by mossy fibers of the dorsal DG. (c) Total number of boutons as a function of distance from the distal end of stratum lucidum, towards CA3, in dorsal and intermediate sections (n = 6 dorsal sections and n = 6 intermediate sections from three mice). (d) Total number of MFBs is statistically similar in dorsal versus intermediate CA2 at the distal‐most 50 μm of the stratum lucidum (dorsal CA2: 5.5 ± 2.25 MFBs, intermediate CA2: 10.33 ± 2.84 MFBs, p = .21, t = 1.34, f = 1.59, n = 6, 6 sections, respectively from 3 animals). (e) Mean bouton density is similar in the distal most 50 μm of stratum lucidum in dorsal sections (a and e1) versus intermediate (b and e2) CA2 (0.00289 ± 0.00112 and 0.00534 ± 0.00128 boutons/μm2, p = .18, t = 1.44, f = 1.31, n = 6, 6 sections, respectively, from 3 animals).