Microscopic study of normal parietal pericardium and unimplanted Puig-Zerbini pericardial valvular heterografts

This investigation used light microscopy and transmission and scanning electron microscopy to study native human and bovine parietal pericardium, ghrtaraldehyde-fixed bovine pericardial patch-grafts, and bovine pericardial cusps of unimplanted Incor or Puig-Zerbini heart valves. The primary objective was to obtain a data base for the future evaluation of postimplantation structural alteration in this valve and in other cardiac valvular bioprostheses constructed of pericardium. The mesothelial cell layer in normal pericardium was best preserved in the bovine tissue. In both bovine patch-grafts and Puig-Zerbini valvular cusps, the serosal surface usually was completely devoid of mesothelial cells and revealed an underlying, finely fibrillar basal lamina. The fibrosa varied in thickness and organization, both within and between the two species, but similar nervous, vascular, and connective tissue components were observed in each. The epipericardial surface was smoother, had fewer elastic fibers, and possessed more surface cells in the human tissue than in the bovine tissue. No evidence of significant tissue degeneration or remodeling was noted in either the stored patch-grafts or heart valves when compared with control bovine and human pericardial tissue layers.