Part of the proposed study is the continuation of the ongoing project. This involves elucidation of the dynamics of follicular population during follicular phase and correlation with the steroid hormones (estrogens, progestins and androgens) in the utero-ovarian vein plasma obtained at the time of ovariectomy. In addition histological examination of the ovaries of steroid treated Baboons will be carried out to study the changes in the distribution of follicular population brought about by this treatment. This will be helpful in understanding the process of ovulation and also will be helpful in proper interpretation of the results obtained so far. For example, studies conducted on this project have shown that ovulation can be induced at a predeterminable time by exogenous administration of steroids. Furthermore, it was shown that the ovary responds to this exogenous steroids only during the latter half of the follicular phase. It was demonstrated that the ovary to contain the dominant follicle is selected by day 9 before ovulation as indicated by increased steroid secretion by this ovary. It was shown that selection of ovulation side does not always alternate from one side to the other in successive cycles. Modern techniques of RIA, the ability to repeatedly collect utero-ovarian vein blood by the use of a laparoscope, and the new method of classification of atretic and healthy follicles will facilitate these studies. These studies will be carried out in Baboons, a non-human primate, which has marked similarities to man. These studies, it is hoped, will give us enough information about the follicular development, based upon which one can design experiments to determine the factors which control the selection of side of ovulation and the selection of the dominant follicle. Based on these one will be able to design a treatment schedule to induce ovulation at a predeterminable time. Preliminary studies demonstrate the feasibility of achieving this goal. Proposed studies also include continuation of the induction of ovulation by steroid treatment. These studies have the potential of practical application in fertility control.