Fig. 4

Representative brain tissue sections photomicrographs from mice of all studied groups; sections stained with silver impregnation technique in the 1st raw (X200) and 2nd raw (X400); thick bundles of long, thick parallel, highly branched nerve fibers of black color (long arrows) appeared in the control group (A, A₁). Thin bundles of short, thin, and less branched nerve fibers (thick short arrows) and short single ones (arrowheads) in the AB-PINACA group (B, B₁). One bundle of thin nerve fibers (curved arrow) and most fibers appeared single, thin, short, and non-branched run in random distribution (zigzagged arrows) in the MDMB-4en-PINACA group (C, C₁). Sections stained with Bromophenol Blue stain in the 3rd raw (X400); Control group (A₂) showed all neurons with a significant positive reaction of blue color (long arrows). AB-PINACA group (B₂) showed moderate reaction within some degenerated neurons (thick short arrows) and mild reaction in the others (arrowheads). MDMB-4en-PINACA group (C₂) showed a minimal reaction in most degenerated neurons (curved arrows) and a few with mild reaction (arrowheads)