Figure 1: Cerebral aneurysm (CA) formation in the rat model. (a) The method for CA induction. As illustrated, the unilateral common carotid artery (CCA) is ligated to induce a compensatory increase in cerebral blood flow in the contralateral internal carotid artery (ICA). As a result of increased hemodynamics, a CA is induced at the anterior cerebral artery-(ACA-) olfactory artery (OA) bifurcation (indicated by the boxed region). MCA: middle cerebral artery. (b) Macroscopic image of the dissected ACA-OA bifurcation indicated as the boxed region in (a). Note that a CA is induced at this bifurcation (arrow). (c, d) Histopathological examination of induced CA by Elastica van Gieson staining. Higher magnified image of CA walls is shown in (d). Note that the disruption of the internal elastic lamina (arrow) and the degeneration of the media, which are histopathological features of human CA walls, are observed. Bar: 50 μm.