Luminal surface of distended arteries by scanning electron microscopy: eliminating configurational and technical artefacts.

Perfusion fixation at physiological pressures, careful tissue handling, adequate drying and reduced beam exposure time eliminated many of the intimal surface projections, ridges and bridges which have been taken for normal structures on scanning electron microscopy. In the normal distended vessel, ovoid endothelial nuclei bulged into the lumen with their major axes aligned in the direction of flow: adjacent cell margins overlapped consistently in the direction of flow, with each cell overlapping the edge of its downstream neighbour. Regular longitudinal furrows associated with undulations of the internal elastin lamina were entirely eliminated from elastic arteries when distending pressures exceeded diastolic levels during fixation.