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KMID : 0894520000040020187
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Development & Reproduction
2000 Volume.4 No. 2 p.187 ~ p.193
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Relationship between Ovarian Development and Plasma Levels of Steroid Hormones , and Induction of Oocyte Maturation and Ovulation in the Cultured Female Korean Sea Bass , Lateolabrax japonicus
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이원교
양석우/곽은주
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Abstract
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Gonad and blood samples were taken from the cultured female Korean sea bass, Lateolabrax japonicus from October to February between 1997 and 1999. Gonadosomatic index began to increase in November and reached the highest value in December (12.8±1.5) and January (14.8±3.5), and then decreased sharply in February (2.6±1.5, p<0.05). The ovarian oocytes developed to tertiary yolk stage and reached fully-Brown stage in December and January, and then underwent atresia without maturation and ovulation in February. The plasma estradio3-17 β level increased from November, and reached the highest value in December (1,152.3±107.2 pg/ml) and January (1,315.4±99.5 pg/ml), after then decreased in February (P<0.05). The concentration of plasma 17 α ,20 β-dihydroxy-4-pregnen-3-one was not significantly changed at low levels (86.6±6.5∼93.8±2.8 pg/ml) during the experimental period (P<0.05). All the fish with fully-grown oocytes in the ovary were matured and ovulated by HCG injection. The number of floating eggs were 325,000±26,000 at HCG 1,000 luhg and 195,000±35,000 at 2,000 lUikg. There was no difference in fertilization rate and hatching rate of the eggs (P<0.05). Considering these results, we could infer that the ovarian oocyte of the cultured Korean sea bass were not matured and ovulated because of the lack of gonadotropin surge. Moreover, HCG injection could induce oocyte maturation and ovulation in the cultured fish, and the effective dose was 1,000 IU/kg.
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KEYWORD
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