9630957 Bahr Production of healthy eggs or oocytes is a crucial process for the regeneration of the species. The oocyte and its surrounding ovarian cells in the ovary constitute the reproductive unit called the follicle. Female organisms invest enormous energy to maintain the growth and development of the follicles. It is logical to assume that a follicle without an oocyte will be eliminated by the body since the follicle loses the potential to provide a healthy oocyte which will develop into an individual after fertilization. However, there is no scientific evidence to support this assumption. Dr. Bahr have proposed a series of experiments to investigate the role of the oocyte on the growth and development of follicle using the chicken as the animal model. In the chicken, the oocyte and cells associated with it is called the germinal disc region (GDR). The first question asked is: will the chicken follicle keep growing or will it die after the GDR is destroyed? If the follicle dies, what is the mechanism underlying it. The second question is: if the chicken follicle dies after GDR destruction, is the replacement of the GDR able to rescue the follicle? Because of the limitations of living animal experiments, Dr. Bahr will conduct this experiment in a tissue culture system mimicking the physiological condition. The last question is: what does the GDR produce that can maintain the growth of the follicle? She will characterize the factor(s) produced by the GDR. The proposed experiments will provide valuable information regarding the role of the oocyte in follicular development and therefore the reproductive success of individual. Because of the similarities in function between the avian germinal disc and the oocyte of other species, it is anticipated that these studies will extend understanding of the control of follicular development in variety of species.