Scanning electron microscopy of normal rabbit aorta: injury or artifact?

The reported morphology of both normal and "injured" aortic endothelium differs significantly from one study to another. To better understand these disparities, we examined the effects of manipulating the preperfusion conditions on the subsequent morphology of normal aortic endothelium in the rabbit. Glutaraldehyde perfusion without any preperfusion with an electrolyte solution, induced vasoconstriction and the accumulation of cellular and plasma protein on the luminal surface of the aorta. Prolonged preperfusion by Ringer-Locke solution and to a lesser extent, by Krebs-Henzleit solution or modified Eagles medium, induced changes in the endothelium similar to those reported as the response to injury induced by other stimuli. Profound vessel wall alterations also occurred in animals which were shocked (through acute blood loss) or killed (by overdose of anesthetic) prior to fixation. These observations may explain, in part, the discrepancies in previous descriptions of the appearance of "normal" rabbit aortic endothelium in SEM, and suggest that the type and duration of the preperfusion must be considered to avoid morphological artifacts.