Figure 2.

Infarct size and angiogenesis assessment by immunofluorescence. (A,B) By NeuN immunohistochemistry, the cortical infarcts were similar in size in both age groups, i.e., 35 ± 3.1% of total cortical volume in young rats and 40 ± 7.9% in aged rats. (C) In the unlesioned hemisphere, CD31-positive blood vessels (green) were rarely detected. (D) By day 14, new blood vessels were emerging in the peri-infarcted area of young animals. The revascularization process in aged animals was delayed and was characterized by the accumulation of CD31-immunopositivity in the fibrotic scar (E). Beyond the fibrotic scar, however, in a region that we dubbed “islet of regeneration,” vigorous angiogenesis was detected in aged animals as well (F). By day 14, mature BV had developed in the peri-infarcted area of young animals (G). Similarly, new, mature blood vessels were detected in the same areas of the aged rats (I). Please note the unexpected expression of CD31 in the wall of the subventricular zone both in young (H) and aged animals (J). (C–J) are Z-projection images. BV, blood vessel; IC, infarct core; IR, islet of regeneration; PI, peri-infarct; Sc, scar; SVZ, subventricular zone.