Effects of estradiol-17b and 17a-methyltestosterone on gonadal sex differentiation in the F₂ hybrid sturgeon, the bester

N. Omoto, M. Maebayashi, E. Mitsuhashi, K. Yoshitomi, S. Adachi, K. Yamauchi-2002

Fisheries Science, 68(5): 1047-1054

Abstract:

The effects of giving oral estradiol-17b (E₂) and 17a-methyltestosterone (MT) on gonadal sex differentiation in the F₂ hybrid sturgeon, the bester (Huso huso female x Acipenser ruthenus male), are investigated. Giving E₂ at 10 µg/g diet to fish from 14 months until 31 months of age induced incomplete feminization and resulted in approximately 40% abnormal ovary development in which oocytes were observed without ovarian lamellar structures and gonadal shape was similar to normal testis. Giving MT at 25 µg/g diet for the same duration failed to induce masculinization, and resulted in approximately 30% undeveloped gonads even at 30-37 months of age. In contrast, E₂ and MT at only 1 µg/g diet given from 3 to 18 months of age was sufficient to induce feminization and masculinization, respectively. In these fish, feminization and masculinization were observed at 9 months, when most putative ovaries and testes were histologically distinguishable by the shape of the gonadal surface. These results indicate that sex reversal can be induced in these fish by hormone treatment that is started at 3 months age, before morphological differentiation occurs on the stroma of the gonads.

(Department of Research and Development, The Hokkaido Electric Power Co., Inc., Ebetsu, Hokkaido 067-0033, Japan, Tel: 81-11-343-8006. Fax: 81-11-385-6558. Email: omoto@epmail.hepco.co.jp)

home