The Center for the Study of Reproduction supports a multidepartmental, interdisciplinary group of faculty who are working jointly on research problems related to mammalian reproductive biology. The faculty has successfully blended its training and investigative efforts over the past twenty years, and has gained collective recognition for excellence of reproductive research. This renewal request seeks funds to maintain and strengthen existing core facilities which provide the framework for the Center. The requested support is for the following core facilities: Core A: Administration; Core B, Assays and Reagents; Core C, Biostatistics; Core D, Laboratory Animal; Core E, Molecular Biology; Core F, Morphology; and Core G, Sheep Research. These core facilities support clinical and basic science faculty who are studying pulsatile patterns of hormone secretion; the regulation of gene expression in reproductive tissue; development and function of pituitary, ovarian, testicular and uterine tissues in vitro and in vivo; the mechanisms of hormone action; the mechanisms by which neuroendocrine systems control reproduction; the influence of photoperiodic rhythms, exercise and nutrition on reproductive behavior and physiology; and the development of new, non- radioisotopic assays. During the last five years, Center investigators have authored approximately three hundred publications in reproductive research, authored more than a hundred publications in research related to reproduction, have substantially increased their funded level of competitively reviewed research support, and have generally distinguished themselves in may arenas related to the objectives of the Center. Over this time the Center has also improved its quality assurance procedures, attracted a number of new investigators to the Center, strengthened areas of clinical and molecular investigation, and delivered more services to more investigators than ever before.