Characterization of progranulin immunoreactivity associated with different types of Aβ plaques in low plaque, high plaque and Alzheimer’s disease cases (a-d). Thioflavin-S staining of Alzheimer’s disease tissue section (low magnification) characterization of PGRN (red) and Aβ- immunoreactive plaques (blue). Triple-color merged image (D) identifies that thio-S plaques have PGRN-positive associated structures but thio-S positive tangles show no PGRN immunoreactivity. Box area in D illustrates areas shown at higher magnification in panels E-H. Scale bar represents 100 μm. (e-h). Higher magnification of area from D showing thio-S positive plaques and tangles (green), PGRN (red) and Aβ (blue). Scale represents 25 μm. Images were acquired with Leica SP8 microscope. (i-l). Low Plaque case: Features of PGRN (green) immunoreactive accumulations (I) around Aβ (red) immunoreactive plaque (j), and merged images (k and l) showing limited overlap (yellow) between PGRN and Aβ. Image D with DAPI-stained nuclei demonstrate the presence of cells around the plaque. (m-p). High Plaque case: PGRN (green)(M) and Aβ (red)(N) immunoreactivity showing more extensive colocalization (yellow) (O and P). (q-t). Alzheimer’s disease case: PGRN (green) (q) immunoreactivity and Aβ (red) (R) show less colocalization (yellow) with the formation of larger AD plaques. PGRN aggregates are present within the Aβ immunoreactive areas but with limited colocalization (Q and T). Three-Dimensional Reconstructions of progranulin-positive Aβ plaques. (u-w). Three-dimensional reconstruction and Mesh rendering of PGRN and Aβ immunoreactive plaques in AD case (U). Mesh rendering of three-dimensional modelled plaque shown in panel (Top view, panel V). The two immunoreactive structures (PGRN-green; Aβ-red) are present as aggregates but show limited areas of interaction (Side view, panel W). Similar patterns of colocalization were observed for LP and HP cases.