show Abstracthide AbstractPurpose: Determine whether sex-determining genes are bivalent at the bipotential stage, poised between the testis and ovary fate, and whether H3K4me3 and H3K27me3 resolve into sex-specific patterns after sex determination, contributing to the canalization and stabilization of either the testis or ovary fate. Methods: XX and XY supporting cells of the gonad were FACS-purified before sex determination (at E10.5) and after sex determination (at E13.5), and submitted to ChIP-seq for H3K4me3, H3K27me3 and H3 as a means to normalize across cell populations. Results: We found that key sex-determining genes are bivalent at the bipotential stage. Genes that are upregulated affter sex determination are stripped of their repressive H3K27me3 mark, whereas repressed genes that promote the alternate pathway remain bivalent even after sex determination. Overall design: ChIP-seq for H3, H3K27me3, and H3K4me3 was performed in duplicate on FACS-sorted XX and XY gonadal supporting cells from E10.5 and E13.5 mouse embryonic gonads. NOTE: processed data was generated from both replicates and is linked to the corresponding rep1 sample records