Fig 3. Histological changes after endothelin-1 (ET-1) injection.

(A-C) Nissl-stained sections of layer V in the hand area of the primary motor area (M1) in a normal intact macaque (A, B) and a macaque 1 month after ET-1 injection (C, Mk-Du). Large pyramidal neurons (>30 μm in diameter) are distributed in the intact M1 (arrowheads in A), as shown in the higher-magnification photomicrograph (B). In contrast, large pyramidal neurons are rarely observed in M1 of the ET-1-injected macaque (C). Scale bars in (A, C) = 500 μm, and scale bar in (B) = 50 μm. (D) Percentage of neurons in each size range in the hand area of M1. Median and interquartile ranges are shown for M1 in intact macaques (n = 6) and for the ipsilateral M1 in ET-1 injected macaques with survival periods of 3 weeks or more (n = 5). (E) Median percentages and interquartile ranges of large pyramidal neurons (area >500 μm²) in the intact M1 (n = 6) and in the ipsilateral and contralateral M1 in the early (≤2 weeks, n = 3) and late (≥ 3 weeks, n = 5) stages after injection. The percentage in the ipsilateral M1 in the late stage was significantly lower than those in the contralateral and intact M1 (*P < 0.05, Kruskal–Wallis one-way analysis of variance and Dunn’s post-hoc test).