Verda E. Agan
Institut Pasteur de Bangui
leads the Reproductive Developmental Biology Group, and holds a secondary appointment in the NIEHS Epigenetics & Stem Cell Biology Laboratory. The main thrust of the group is to define the normal process of how gonads and reproductive tracts form during embryogenesis and investigate whether this process is susceptible to in utero exposure to endocrine disruptors. Compelling animal evidence and human epidemiological data have revealed that impairment of fetal organ development has profound consequences on adult health. The concept of "fetal origins of adult diseases" also applies to the reproductive systems where formation of most reproductive organs is completed before birth. Defects in reproductive organ formation manifest as birth defects in severe cases, i.e., pseudohermaphroditism. However, minor abnormalities are often left undetected and become a potential cause of fertility problems and neoplasia when the affected individual reaches adulthood. The Reproductive Developmental Biology Group uses organogenesis of the gonads as a model to understand the basic process of organ formation and the potential implication of the impacts of endocrine disruptor exposure to gonad development in fetuses and fertility in adulthood. Gonads are one of the few organs that exhibit dramatic sex-specific pattern of dimorphic development. This unique pattern of development provides a model to understand not only the mechanism of sex determination, but also how progenitor cells make the decision to differentiate into tissue-specific cell types, the fundamental concept of embryology.
Understanding how different somatic cell lineages — Sertoli and Leydig cells in the testis and granulose and theca cells in the ovary — are established in the fetal testis and ovary, respectively. Defining the cellular processes that lead to the formation of testis architecture and follicle assembly in the ovary. Investigating the effects of in utero exposure to endocrine disruptors on gonad organogenesis and lingering impacts on fertility in adulthood.
Current projects: Exploring the potential extra-gonadal origin of fetal Leydig cells in the testis and theca cells in the ovary and the involvement of the Hedgehog pathway in this process.