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.
fatty tissue connective tissue made of fat cells in a meshwork of areolar tissue. fibrous tissue the common connective tissue of the body, composed of yellow or white parallel elastic and collagen fibers. gelatinous tissue mucous tissue.ibrous tissue, the connective tissue of the body, consisting of closely woven elastic fibers and fluid-filled areolae. Also called fibroelastic tissue. Compare areolar tissue. See also connective tissue.