A cyp19a gene that contains nine exons and eight introns was identified from Carassius auratus and was mainly expressed in the ovary. The cyp19a mRNA level after hatching was initially low, but began to increase from 25 days after hatching. A number of cis-acting elements, such as the oestrogen receptor, steroidogenic factor 1 and SOX-5 recognition sites, were found in the promoter of the cyp19 gene, which possesses a promoter function confirmed by a recombination green fluorescent protein checking system in vitro.
