Embryonic gonads were micro-dissected at according stage, removed from the mesonephros and incubated in 0.05% trypsin for 5 minutes at 37C. Gonads were then mechanically dissasociated in PBS/3% BSA and passed through a filter cap to obtain a single cell suspension. Fluorescently-labeled cells were collected by Fluorescence Activated Cell Sorting (FACS). For ATAC-seq, 60K cells were collected per replicate. For ChIP-seq, 50-100K cells were collected per replicate. ATAC-seq libraries were prepared according to Buenrostro et al.2013. ChIP-seq libraries were prepared according to Van Galen et al., 2016. For ChIP-seq, corresponding H3 ChIP was used as Input.