Biochemistry Experts

Humphrey Yao

Developmental Biology
Institut Pasteur de Bangui

Humphrey Yao


Humphrey Yao, Ph.D., 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.

Research Interest

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

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