Acta Neuropathol (2011) 122:293–311 301 Fig. 4 Intensive astrogliosis with concomitant laminin over-expres- sion is already present in the early-stage TG arcAb mouse brain. a Representative cortical brain section of an early-stage TG arcAb mouse triple-stained for GFAP, laminin and Ab/APP. Only few diffuse Ab plaques and little vascular Ab deposits were seen at this age. However, the presence of astrogliosis (GFAP staining) around some incoming leptomeningeal vessels and arterioles (a, arrows) and small vessels (a, asterisks) in the cortex was already detected at this age with a concomitant increased immunopositivity for laminin. b A 920 of a representative cortical brain section of an early-stage TG ImmunoResearch Laboratories, USA) used to visualise the primary anti-b dystroglycan antibody which was raised in mouse, explaining the presence of both b dystroglycan and endogenous mouse IgG on the same brain sections. Adjacent brain sections immuno-stained with FITC-conjugated don- key anti-mouse IgG secondary antibody only showed the same IgG staining pattern (data not shown). Interestingly, an area of the brain where no extravasated mouse IgG could be observed (the hypothalamic region, Fig. 6c) did show a sig- niﬁcantly less pronounced loss of b dystroglycan expression arcAb mouse triple-stained for GFAP, laminin and Ab/APP. Astro- cyte (GFAP) and laminin staining showed expression and/or secretion of laminin in the astrocytic dendrites (arrows) and surrounding the astrocytes (asterisk). Western blots showing a higher amount of laminin in the media of ex vivo astrocyte cultures from early-stage (c) and mid-stage (d) TG arcAb mice as compared to that of astrocytes from their NTG littermates. Scale bar a 300 lm; b 30 lm. Hue settings of ﬂuorescence for Ab were altered for more contrast effect explaining the purple colour (Fig. 6c and g). This area was also spared from diffuse Ab plaques and Ab was rather present as CAA. b-amyloid-related pathology of cerebral arteries and arterioles in late-stage arcAb mice Vascular corrosion casts and SEM were used to study the vascular morphology in brains of TG and arcAb NTG mice. Severe alterations were seen especially in the morphology of arteries and arterioles of late-stage TG animals as compared 123