Fig. 3

Morphological features of axonal degeneration and associated pathologies in the anterior insula visualized using Bielschowsky silver staining. Axonal thinning and associated myelin changes (*) were visible in fibers in PD_5 (a-c). Axonal thickening was seen in PD_4 dysgranular insula (d), thinning and spheroid body in PDD_1 agranular insula (e), and DLB_5 and DLB_7 in both sub-regions (f, g). Multiple fibers were surrounded by β-amyloid plaques in PD_3 (j) and PDD_3 with bulbous swelling in nearby axons in agranular insula (h, i). Early NFTs were seen in PD_3 dysgranular insula (k) and in PDD_6 agranular insula where dystrophic neurites and peri-somatic granules were also present (l, m). In DLB_9, multiple perivascular amyloid-β plaques were visible (n). NFTs as well as severe axonal degeneration were present in DLB_1 (o), DLB_8 (r) and DLB_9 which showed ghost tangles (p, q) surrounded by AG (p,r,s; upper right corner). AGs are featured as comma-shaped deposits. Magnification 630 × ; Scale bars: 50 μm. AG: argyrophilic grains; DLB: dementia with Lewy bodies; NFTs: neurofibrillary tangles; PD: Parkinson’s disease; PDD: Parkinson’s disease dementia