Global Gene Expression in the Human Fetal Testis and Ovary

This study describes a temporal profile of gene expression from normal human fetal testes and ovaries. Gonads from 34 fetuses between 9 weeks and 20 weeks of gestation were obtained from the Department of Pathology and the Birth Defects Research Laboratory at the University of Washington. Relative transcript levels were determined using the Affymetrix Human Genome U133A Plus 2.0 arrays. Sex determination occurs in the human gonad at approximately 6 weeks gestation with development of the testis driven by expression of SRY. In this study, SRY transcript was present and elevated at 9 weeks gestation in the testis but absent in the ovary. The transcript levels of other testis-specific factors SOX9, AMH, and the steroidogenic genes CYP17a1, CYP11a1, STAR and HSD17β3 were all significantly higher in the testis. In contrast, transcripts known to be involved in meiosis including STRA8, SPO11, SYCP3, TEX11, TEX14 and STAG3 showed highest expression in the fetal ovary beginning at week 12. These gene expression profiles will be a resource for understanding and defining normal gonad development and provide the opportunity to dissect abnormal development. Gonads from 34 fetuses between 9 weeks and 20 weeks of gestation were obtained, total RNA was extracted and hybridized to Affymetrix microarrays.