This is the continuation of a research program of long standing, designed to elucidate the neuroendocrine control systems which govern reproductive processes in the rhesus monkey, a representative primate. Much of what is learned using this experimental model has been and continues to be applicable to the understanding of human reproductive physiology. During the next project period the functioning of the hypothalamic LHRH pulse generator will be studied in unrestrained females throughout the normal menstrual cycle, pregnancy, lactation and the advent of puberty. The influence of mild pertubations in the environment will also be investigated. Pulse generator activity will be assessed using electrophyciological techniques couples with radiotelemetry permitting continuous monitoring of this control system in freely behaving animals. In addition, the ongoing study of the influence of various ovarian factors, other than estradiol and progesterone, on the hypothalamic LHRH pulse generator will be continued.