Binding of specific cell or tissue structures (usually proteins) by an antibody directed against that protein. This antibody is often raised in a species other than the one from which the specimen is taken. For example, antibodies may be developed in rabbits to a protein present in human tissue. There are several methods for visualizing where these antibodies have bound to the tissue. In the example above, other antibodies directed against rabbit proteins that are bound to something that can be visualized (either via fluorescent properties or by chemical reaction) will bind to places in the tissue that contains the protein in question. Therefore, you can see where the protein is distributed in the tissue.
