Ovarian follicles are the functional units of the ovary and are responsible for a woman’s fertility and ovarian endocrine function. Currently, young women and prepubertal girls facing cancer diagnosis have limited options to preserve their fertility, with cryopreservation of ovarian tissue prior to chemotherapy the best available option. The challenge is that the vast majority of the follicles that survive the cryopreservation are early-stage primary and primordial follicles, and the subsequent success rate of their development and maturation in vitro is very low. These low success rates are attributed to the complex and poorly understood paracrine, autocrine and endocrine signaling between the cells in a follicle. Our goal is to identify the key signals and transcription factor activity during early stage follicle development that will result in a culture system design that maximizes follicle growth, health, and development. We have employed the TRACER assay developed by Dr. Lonnie Shea's research group to track transcription factor activity in real time and we have also employed microarray analysis to compare gene expression profiles in different culture systems.