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. 2018 Sep 18;5(5):ENEURO.0102-18.2018. doi: 10.1523/ENEURO.0102-18.2018

Figure 1.

Figure 1.

Morphology of porcine hippocampus. Sagittal and coronal sections of porcine brain were stained histologically to show organizational structure. A, Coronal (top) and sagittal (bottom) sections stained with LFB/CV show white and gray matter composition in dorsal hippocampus, which can be accessed stereologically from the brain surface. Both coronal and sagittal cuts through hippocampus produce arrow-like structures with consistent anatomic layers (scale = 2 mm). B, Coronal section stained with CV showing gyrencephalic structure (bregma –1.5mm). Deep brain structures including hippocampus (dorsal and ventral) and thalamus are visible (scale bar = 2 mm). C–E, Hippocampal layers including the alveus (A), stratum oriens (O), stratum pyramidale (P), stratum radiatum (R), stratum lacunosum-moleculare (L-M), stratum moleculare (M), and stratum granulosum (G) are clearly visible (scale bar = 100 μm). C, Staining with LFB shows the myelinated axons, while counterstaining with CV highlights neurons in the pyramidal and dentate cell layers. Columns on the left show the width of corresponding hippocampal layers quantified from H&E-stained sections in Yucatan pigs (bregma –1.5 mm; n = 8) and Long-Evans rats (bregma –4.2 mm; n = 6). The widths for the pig hippocampal layers are (in μm, mean ± SEM) A = 173.8 ± 11.55, O = 178.3 ± 15.01, P = 213.2 ± 15.9, R = 394.1 ± 22.36, L-M = 223.1 ± 11.7, M = 335.1 ± 17.85, G = 81.3 ± 4.5. The corresponding widths for rat hippocampal layers are (in μm): A = 69.1 ± 9.05, O = 144.4 ± 7.51, P = 53.1 ± 1.9, R = 343.9 ± 12.33, L-M = 112.2 ± 8.21, M = 232.8 ± 11.35, G = 90.6 ± 3.52 (scale bar = 200 μm). The following hippocampal layers were significantly larger in pigs than in rats: stratum alveus by 152% (p < 0.001), pyramidale by 301% (p < 0.001), radiatum by 15% (p < 0.05), lacunosum-moleculare by 99% (p < 0.001), and stratum moleculare by 44% (p < 0.01), whereas the stratum oriens and granulosum were not significantly different. D, Staining with MAP2 identifies location of dendritic arbors, which are densely packed. E, A subpopulation of interneurons is identified using parvalbumin (PV) IHC in pyramidal and dentate granule cell layers. F–H, The pyramidal CA1 layer (scale bar = 50 μm). F, The pyramidal CA1 cell layer is widely dispersed, similar to the human CA1 layer, as shown with LFB/CV staining. G, Pyramidal CA1 cells send their dendrites down toward the hippocampal fissure as highlighted with MAP2 staining. H, PV+ interneurons located above, inside, and below pyramidal CA1 layer send their projections into stratum radiatum.