The overall objectives of this project are to characterize the typespecific and interspecific antigens of erythrocytes (erythrogroups), serum (serogroups), isozymes (zymogroups), and other tissues --especially reproductive tissues -- in rhesus monkeys. These immunogenetic markers are then studied for their intrinsic interest as well as for their possible roles in reproduction and development. Specifically, we have produced and characterized over 25 blood typing reagents which detect erythrogroups in at least 10 independent genetically controlled blood group systems. These markers have been very useful in solving cases of disputed parentage and for identification of individual monkeys in experiments that require unequivocal identification. In addition to the erythrogroups, we have defined at least two genetically controlled serogroups (allotypes); one is carried by alpha-microglobulin molecules and the other by gamma globulin. The isozyme systems appear very promising especially for use in reproductive studies. Both LDH-X and PGK-B enzymes have been detected in rhesus testes. Using all of these immunogenetic markers, we estimate that well over a million unique genotypes can now be detected in the rhesus monkey. BIBLIOGRAPHIC REFERENCE: Immunogenetic Studies of Rhesus by W.H. Stone, Chapter 11 The Rhesus Monkey. Vol.II. ed. G.H. Bourne, Academic Press, 1975.