Figure 6. Male sex determination. General transcription factors, like LHX1, EMX2 and PAX2, are necessary for intermediate mesoderm development. The gonadal ridge differentiates from the intermediate mesoderm following the action of SF1, which is regulated by LHX9 and WT1. SRY expression, activated by WT1 and GATA4, induces testis differentiation, characterized by an increase in SOX9 and a decrease in DAX1 expression. The effect of SRY overcomes the action of genes that have been proposed to repress testicular differentiation, like WNT4, RSPO1, β-catenin and FOXL2.