Ultrastructural characteristics of dog and human platelets adherent to native and collagen-coupled cuprophan.

Adhesion of human and dog platelets to native and collagen-coupled Cuprophan under defined flow conditions was studied by scanning and transmission electron microscopy. Dog platelets, singly adherent to and uniformly distributed on both native and collagen-coupled Cuprophan, extend slender pseudopods across the surface without evidence of degranulation. Human platelets, while not adhering to native Cuprophan, formed irregularly shaped, semi-confluent cytoplasmic sheets on the collagen-coupled surface. Extensive cytoplasmic reorganization and degranulation suggests a post-release state of the human platelets. Aspirin had no apparent effect on either human or dog platelet adhesion or upon the apparent release state of the human platelets.