title: Gonadogenesis and Sex Differentiation in the Korean Rose Bitterling,Rhodeus uyekii).
abstract: This report describes the sex differentiation of the Korean rose bitterling,Rhodeus uyekii, from hatching to 170 days post-hatch (DPH) in relation to total length (TL), body weight (BW), and integral water temperature (IWT). The growth curve of TL from just hatching to 83 DPH was 5.144e0.045t(R² = 0.961; t, time), and that of BW was 2.398e0.086t(R² = 0.725). Primordial germ cells (PGCs) were observed at 17 DPH (7.9 mm TL, 3.74 mg BW, 374°C IWT), and thereafter began to protrude into the peritoneal cavity. At 21 DPH (9.2±0.14 mm TL, 4.8±0.07 mg BW, 462°C IWT), some PGCs contained condensed chromatin and oocyte were observed in meiotic prophase. In contrast to the ovaries, which grew gradually after sexual differentiation, testes began multiplying at 25 DPH (10.1 mm TL, 5.42 mg BW, 550°C IWT), when testicular differentiation was first identified, and multiplied continuously thereafter. At 33 DPH (11.2 mm TL, 10.5 mg BW, 726°C IWT), the developing testes contained spermatogonia that exhibited mitotic activity. No spermatocyte or sperm cell was observed until 83 DPH (18.9 TL, 48.2 mg BW, 1,826°C IWT). At 170 DPH (32.5 mm TL, 270.1 mg BW, 3,740°C IWT), which was the end point of this study, the mature ovaries showed germinal vesicle breakdown, while the mature testes contained observable spermatocytes and sperm cells. These results allow us to identify the sex differentiation type of the Korean rose bitterling as differentiated gonochoristic.
authors.affiliation: Inland Aquaculture Research Center, National Institute of Fisheries Science (NIFS), Changwon 51688, Korea.
authors.forename: In Bon
authors.initials: IB
authors.lastname: Goo
authors.affiliation: Inland Aquaculture Research Center, National Institute of Fisheries Science (NIFS), Changwon 51688, Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Kim
authors.affiliation: Inland Aquaculture Research Center, National Institute of Fisheries Science (NIFS), Changwon 51688, Korea.
authors.forename: Myung Hun
authors.initials: MH
authors.lastname: Kim
authors.affiliation: Inland Aquaculture Research Center, National Institute of Fisheries Science (NIFS), Changwon 51688, Korea.
authors.forename: Hye-Sung
authors.initials: HS
authors.lastname: Choi
authors.affiliation: Biotechnology Research Division, NIFS, Busan 46083, Korea.
authors.forename: Hee Jeong
authors.initials: HJ
authors.lastname: Kong
authors.affiliation: Inland Aquaculture Research Center, National Institute of Fisheries Science (NIFS), Changwon 51688, Korea.
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Division of Marine Bioscience, Korea Maritime and Ocean University, Busan 49112, Korea.
authors.forename: In-Seok
authors.initials: IS
authors.lastname: Park
keywords:  Rhodeus uyekii; Early growth; Gonadogenesis; Sex differentiation