Sulf1 expression is down-regulated in the developing male UGS. Expression of Sulf1 in the UGS was quantified by real-time RT-PCR with expression values normalized to the 18S mRNA. A, Sulf1 expression was not significantly different in the male and female UGS at e16 or e17, but expression was dramatically down-regulated in the male UGS by e18. To further clarify the expression of Sulf1 in the developing UGS, e16 UGSs were dissected to separate the UGE and UGM, and Sulf1 expression was measured in the separated tissues by real-time RT PCR. The UGM-specific gene vimentin and UGE-specific gene cytokeratin-19 were also assayed to determine the relative purity of the separated tissues. B, Sulf1 expression was primarily in the UGM. Expression of the control genes indicated that the UGM was approximately 94% pure and the UGE approximately 84% pure. Error bars indicate sem. Statistical significance was determined by ANOVA with Bonferroni correction post hoc analysis. *, Comparisons where statistically significant (P < 0.001) differences in expression were observed.