Abstract
A new ovarian cell line, CSO , was established from half‐smooth tongue sole Cynoglossus semilaevis . Primary culture of CSO cells was initiated from digestion of ovarian tissues pieces by trypsin solution and cultured at 24° C in Dulbecco's modified Eagle's medium– F12 medium ( DMEM – F12 , 1:1) (pH 7·0), supplemented with 20% foetal bovine serum, basic fibroblast growth factor ( bFGF ), epidermal growth factor ( EGF ), insulin‐like growth factor‐I ( IGF ‐I) and human chorionic gonadotropin ( HCG ). The cultured CSO cells, fibroblastic in morphology, proliferated to 100% confluency 3 days later and had been subcultured to passage 80. Chromosome analyses indicated that the CSO cells exhibited chromosomal aneuploidy with a modal chromosome number of 42 that displayed the normal diploid karyotype of C. semilaevis [2 n = 42 t, fundamental number ( N F ) = 42]. Reverse transcription polymerase chain reaction revealed that CSO cells could express ovarian somatic cell functional genes p 450 armo , foxl2 and sox9a but not ovary germ cell marker gene vasa and male‐specific gene dmrt1 . Transfection experiment demonstrated that CSO cells transfected with pEGFP‐N3 plasmid could express green fluorescence protein ( GFP ) with higher transfection efficiency. The CSO cell line might serve as a valuable tool for studies on the mechanism of sex determination and oogenesis of ovary in flatfish.