This project deals with the use of a group of antibodies called anti-idiotypes. These antibodies recognize specific receptors, which are the mechanism by which hormones and transmitters recognize and stimulate specific cells. The receptors involved in this study are ones which recognize the brain hormones vasopressin and corticotropin releasing factor. The major work to be done involves demonstrating various characteristics of these antibodies including specificity, binding ability, and the methods needed to apply them in histological sections. Receptors are an extremely important group of proteins in the body; the successful use of anti-idiotype antibodies to study their structure and function represents a significant advance in biological sciences.