brain tissue, artery, nerve bundle, tumor (possibly), bone fragment, meningeal tissue, blood clot, cerebral ventricle, cranial cavity wall, surgical implant, microvascular network, lymph node, ductus arteriosus, aortic valve, ventricular septum, endocardium, atrial appendage, myocardial tissue, cardiac catheter ( possibly), arteriovenous malformation, embolus, neurofibrils, glial cell cluster