John J. Eppig

I am a developmental/reproductive biologist studying the development of mammalian oocytes, the cells that become eggs. The focus of my research is on the complex interactions between developing oocytes and their companion follicular somatic cells, the granulosa cells. I found that oocytes are not simply passive recipients of nutrients and signals from ovarian follicular somatic cells, as once believed, but rather actively promote the functions of somatic cells needed to support oocyte development and regulate meiosis. I originated the concept of an oocyte-granulosa cell regulatory loop in which bi-directional communication between the oocyte and companion granulosa cells is essential for both normal oocyte and follicular development. A major goal of my current research is to define the components of this regulatory loop and their functions. I also achieved the first complete development of mammalian oocytes in vitro. This included in vitro initiation of primordial follicle development, oocyte growth, and acquisition of competence to undergo maturation, fertilization, and, after transfer of preimplantation embryos to foster mothers, the birth of live young. Finally, I am the Principal Investigator of a Program Project to develop mouse mutant models of infertility using ENU mutagenesis.