The major objectives are: (1) to search for functional evidence of local control mechanisms within the uteroovarian vascular complex in rhesus monkeys which may be involved in the transfer of hormones or other materials between the uterus and ovary and thus serve to regulate corpus luteum function. If evidence for the transfer of such physiologically important materials as progesterone or monkey chorionic gonadotropin is found, additional functional and anatomical determinations will be made to define the venoarterial or other local pathways involved. A latex injection and tissue clearing technique will be utilized for gross anatomical determinations. Methods for light and electron microscopy will also be applied. (2) to relate rate and distribution of blood flow within the ovary and uteroovarian vascular pedicle to the varying levels of corpus luteum activity found during the menstrual cycle, various stages of pregnancy and lactation. If major alterations in rate and/or direction of blood flow are noted, investigations designed to evaluate the physiological significance of these alterations as well as the hormonal and nervous controls involved will be performed. The technique employing radioactive microspheres will be the primary one utilized for these purposes. Ancillary techniques to be employed include radioimmunoassay of steroid and gonadotropic hormones for determination of the endocrine status of an animal, laparoscopy for gross confirmation of ovarian activity and cineangiography for evaluating vascular pathways and direction of blood flow.