Figure 3

Apoptosis, microglial activation and a decrease in PCNA-positive cells at 24 h after irradiation. We quantified cleaved caspase-3 (CC3), Iba1, PCNA and Sox2 immunostainings in the embryonic brain of controls and 1.0-Gy-exposed mice. More specifically, we analysed changes in the region surrounding the lateral ventricle (LV) (as delineated in (A) and (C)) at 24 h after radiation exposure. (A-E) CC3 immunoreactivity showed a marked increase in apoptosis in the upper cortical layer in the 1.0-Gy-irradiated brains (C, D, E), as compared to the control condition (A, B, E). (B) and (D) are magnifications of the CC3 staining shown in (A) and (C). (F-H) Iba1 staining revealed an increase in the Iba1-positive area following irradiation (G, H), when compared to non-irradiated embryonic brains (F, H). An enlargement of Iba1-positive microglial cells which engulf apoptotic nuclei is provided in the upper right corner in (G). (I-K) A decreased PCNA-positive area was observed after 1.0-Gy radiation (J, K), compared to non-irradiated controls (I, K), while (L-N) no significant changes in Sox2-positive progenitor cells were observed in the irradiated brains (M, N), as compared to control embryos (L, N). Data are presented as mean ± SEM. *P < 0.05, **P < 0.01 for comparison with controls. The number of animals used per test is indicated in the graphs (N). Scale bar: 20 μm (100 μm in (A) and (C)).