Fig. 1
Chronic mild hypoxia (CMH) triggers vascular leak in cerebral blood vessels associated with microglial clustering. Frozen brain sections taken from mice exposed to normoxia or 7 days hypoxia (8% O2) were stained for the following markers: a the endothelial marker CD31 (AlexaFluor-488) and fibrinogen (Cy-3); d fibrinogen (Cy-3) and Mac-1 (AlexaFluor-488); e CD31 (AlexaFluor-488), fibrinogen [Cy-5 (blue)] and Mac-1 (Cy-3); f CD31 (AlexaFluor-488), IgG (Cy-3) and Tmem119 [Cy-5 (blue)]; and g, Mac-1 (AlexaFluor-488). All images were captured in the brainstem. Scale bars = 100 μm (a) and 50 μm (d–g). b, c Quantification of the number of leaky (fibrinogen-positive) blood vessels/FOV (b) or total area of vascular leak/FOV (c) in the brainstem after 4, 7, or 14 days hypoxia. h Quantification of the morphological categorization of microglia under different conditions. All results are expressed as the mean ± SEM (n = 4 mice/group). **p < 0.01 versus normoxic conditions. Note that CMH provoked transient vascular leak in brainstem blood vessels that was associated with wrapping of Mac-1/Tmem119-positive microglial processes around the damaged vessel and with a morphological switch from ramified to activated morphology (g)