An agent that is smaller than a virus causes scrapie. It is either a protein called a prion or it is another substance closely associated with the prion protein. Scientists still have a lot to learn about the scrapie agent and exactly how it works.
Tissue valves are made with tissues from porcine (pig) heart valves or bovine (cow) cardiac tissue because they function like human heart valves. Once the tissue is removed from the animal, it is chemically treated to preserve the tissue and prevent immulogic reactions once it is placed in a patient.
Cardiac tissue is made of cardiac muscle cells and a small amount of connective tissue. The cells that make this tissue are called cardiocytes. They have the special ability t â¦ o beat on their own with no nerve stimulation. If one touches another beating cell, they will begin to beat together.ells make up tissues, and tissues make up organs.tissues are group of cells which perform similar action.so they are made up of cells only. 3 people found this useful. Edit.