SINOPSIS

Marine mammals experience unique physiological conditions when diving. Myocardial function is sustained despite a 90% reduction of the blood flow in the coronaries. Therefore, their heart valves and pericardium could serve as a unique source of tissue for the manufacture of prosthetic heart valves. The pericardium of a stillborn pup sea lion was investigated to determine its morphology using gross observation, scanning electron microscopy (SEM), light microscopy, and transmission electron microscopy (TEM). Depending upon the site of sampling, the structure of the pericardium varied significantly. The atrial sample was well structured with wavy bundles of collagen fibers. The thickness in the atrial sample was regular with a smooth serous surface. The fibrous side of the pericardium of the auricular sample was irregular and incorporated microcapillaries. Both the sternoperitoneal ligament and the phrenoperitoneal ligament section were irregular and incorporated various amounts of adipocytes. Because of the increased amount of adipocytes, the fibrils of the collagen fibers were also observed to be occasionally agglutinated. Practically, the harvesting of pericardium would have to be restricted to the atrial surface. The presence of adipocytes in the pericardium wall makes the selection of this tissue a poor choice compared to alternative existing tissue sources.