Gene expression in XY oestrogen-treated gonads cultured from day 25 of gestation for 5 days. Quantitative PCR for key male markers SRY, SOX9, AMH and FGF9 (a), and key female markers FOXL2, RSPO1, WNT4 and FST (b) during gonadal culture in control (open bars) and oestrogen-treated (black bars) gonads. Both SRY and AMH mRNA levels were significantly suppressed (P < 0.001) in the sex-reversed gonads. However, SOX9 mRNA levels were unchanged (P > 0.5). There was significant upregulation of the ovarian genes FOXL2 (P < 0.004) and WNT4 (P < 0.02) in sex-reversed gonads, while FST was unchanged and RSPO1 was significantly downregulated (P < 0.001) in the presence of oestrogen.