Photomicrographs showing a bifurcation type aneurysm. Hematoxylin and eosin staining. (a) Pathological findings 1 week after the embolization showing no organization. (b) Pathological findings 2 weeks after the embolization showing no organization. (c) Pathological findings 3 weeks after the embolization showing partial organization. (d) Pathological findings 4 weeks after the embolization showing organization of the whole aneurysm.