Images of immunolabeling with the β-amyloid (Aβ) antibody 6E10, phosphorylated tau (pTau) and active caspase-3 in the forebrain of 3

<p>×<b>Tg-AD mice.</b> 6E10 labeled cortical neurons in layers V and VI in the frontal cortex (FC) in 18- (A), 20- (B) and 24- (C) month old transgenics. Extracellular Aβ deposition appeared largely as diffuse plaques that were present in the cortex by 20 (B), but became common at 24 (C), months of age. Note the large number of plaques in the septum of both 20- and 24-month old transgenic mice. In the olfactory bulb, diffuse plaques appeared in the granule cell layer in 24 month-old animals (C, F); no 6E10 labeled neurons were seen in the olfactory bulb (OB) at any age point (D-F). Panels G-L show p-Tau labeling in the cortex, hippocampal formation and olfactory bulb in a 24-month old animal. Distinct labeling was seen in hippocampal CA1 pyramidal neurons and their processes, including axons in the alveus (Alv; G, H). A few CA1 pyramidal neurons exhibited tangle-like pathology (arrows in H). A small number of cortical pyramidal neurons also showed clear p-Tau immunoreactivity (I). p-Tau immunoreactive somata were not seen in the main olfactory bulb (J, L), but were present in the deep part of the piriform cortex (J, K). In contrast, p-Tau labeling was seen in the nerve fiber layer (NFL; L). No overt nuclear labeling of active caspase-3 was detectable in the forebrain in 24-month old animals (M-O). RMS: rostral migratory stream. Other abbreviations are defined in the legend for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037599#pone-0037599-g002" target="_blank">Figure 2</a>. Scale bar = 2 mm in A applying to B-C, M; equal to 1 mm in G, 100 µm in F, and 200 µm for remaining panels.