The enumeration, i.e. measurement of the total number, of defects or lesions of the internal elastic lamina which are not hyperplastic or neoplastic in origin in a specified sample of artery. A lesion is a localized pathological change in structure of an organ or tissue due to injury or disease; especially one that is circumscribed and well defined. The internal elastic lamina (IEL) is a fenestrated (perforated) layer of elastic tissue, i.e., one having the property of returning to the original shape after being distorted, that is the outermost part of the intima (innermost layer) of an artery. The IEL is the elastic layer that is situated between the tunica intima (inner layers) and tunica media (middle layers) of artery walls. An artery is any one of the branching system of muscular, elastic blood vessels that carry blood away from the heart.