The ultimate goal of this project will be to examine the specific effects of estrogen and progesterone on immunoglobulin concentrations within the female and male reproductive tracts, specifically the uterus and seminal plasma in rabbits. Several studies ovarian hormones have varying influences on the resistance of the uterus to infection in several species and that antibacterial activity may exist within the seminal plasma. Sixty mature New Zealand White Rabbits (50 females, 10 males), will be randomly assigned to six groups in a split plot factorial design, with ten animals per group. The primary objectives will be to compare ovariectomized and intact rabbits to (1) quantify the immunoglobulin concentrations in uterine fluid, serum, and seminal plasma; (2) quantify the antibacterial activity of uterine fluid and uterine-derived leukocytes, seminal plasma, and serum. These experiments will provide a database to correlate the relationship between ovarian hormones, antibacterial activity, and immunoglobulins as they regulate reproductive defense mechanisms; and determine the role of sex hormones in regulating specific immunoglobulins and determine a possible relationship between female and male infertility due to the antibody level responses occurring within the genital tract.