Fig. 2

Microglial phenotypes in post-mortem TBI immunochemistry. The pattern and extent of microglial reactivity may vary according to species and injury severity. Representative images of Iba-1+ microglia display ramified (a), hypertrophic (b), and bushy (c) morphologies after moderate-level controlled cortical impact in rodents (scale = 25 µm; images adapted from Henry et al. [62]). Human post-mortem studies demonstrate morphologically altered CR3/43+ microglia after a single moderate-to-severe TBI (d) (scale = 100 µm; images adapted from Johnson et al. [5]). In a closed-head rotational acceleration model of TBI in pigs, Iba-1+ microglia display ramified morphologies in sham conditions (e) and after acute mild TBI absent permeabilized neurons (f) yet display ameboid morphology after acute mild TBI localized with permeabilized neurons (g) (scale = 25 µm; images adapted from Wofford et al. [59]). In this same model, Iba-1+ microglia have been shown to undertake a more ramified phenotype after single mild TBI at longer timepoints post-injury. Representative images of Iba-1+ microglia compare morphology in sham (h) and 7-day postinjury (i) in the hippocampal hilus, and sham (j) and 1-year post-injury (k) in the hippocampal molecular layer (scale = 50 µm; images adapted from Grovola et al. [67])