Follicle Selection and Differentation in the Avian Ovary

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In all birds, reproduction (ability of the ovary to produce eggs) is dependent upon the initial development of a group of small, undifferentiated ovarian follicles. It is from this cohort that a single follicle is selected, often on a daily basis, to initiate growth prior to ovulation. The novel concept tested is that follicle selection, followed immediately by rapid growth and final differentiation, is dependent upon the acquisition of Follicle-Stimulating Hormone (FSH) and Vasoactive Intestinal Peptide (VIP) receptor responsiveness. Initial studies using the domestic hen as the primary research model will establish the cellular mechanisms that prevent receptor signaling and maintain follicles in an undifferentiated state prior to follicle selection. One objective of the project is to test the hypothesis that ovarian follicle selection in birds represents a process in which a single undifferentiated follicle per day escapes inhibitory mechanisms and begins rapid growth and final maturation prior to ovulation. A second objective will focus on cellular mechanisms that regulate follicle growth and differentiation immediately subsequent to selection, including the initiation and entrainment of circadian rhythms within the ovary. The data generated from these studies are expected to: 1) enable initial predictions about mechanisms regulating follicle selection in non-avian vertebrates (e.g., reptiles and mammalian species); 2) describe cellular mechanisms that determine a bird's reproductive potential, and possibly identify mechanisms that enable multiple ovulations in mammals (including fraternal twins in humans); and 3) have practical implications to enhancing fecundity in both threatened/endangered species and food-producing animals. Research results will be regularly presented at professional society meetings, and all completed studies will be published in high quality research journals in a timely fashion. The funding provided will support both undergraduate and graduate student research projects. The Principal Investigator actively recruits and encourages the participation of women and students from underrepresented populations.