Preserving the original architecture of elastin components in the formic acid-digested aorta by an alternative procedure for scanning electron microscopy.

The present study examined procedures of specimen preparation for observing elastin components in the formic acid-digested tissue by scanning electron microscopy (SEM). The rat thoracic aorta fixed in 4% paraformaldehyde was treated with 90% formic acid for 85-96 hr at 45 degrees C and processed in two different ways: 1) the tissues were freeze-dried directly from water and 2) they were treated with tannic acid and osmium followed by critical point drying. The former procedure caused marked deformation of elastin components, while the latter preserved them well in shape and arrangement. Thus, the three-dimensional organization and ultrastructure of the elastin components were precisely demonstrated in this study.