• 한국어류학회지
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• 제20권4호
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• pp.255-262
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• 2008

멸종위기야생동식물 1급으로 지정된 꼬치동자개, Pseudobagrus brevicorpus의 종복원을 위해 인위적인 교배를 통하여 획득한 자치어를 대상으로 성분화 과정을 조사하여 성적임성 여부를 확인하였다. 부화 후 4~5일째 자어에서 생식융기 1쌍이 장과 중신관 사이에서 관찰되었고, 그 후 유사분열이 활발히 진행되었다. 부화 후 20일째 치어에서 난원세포의 출현으로 난소 분화가 시작되었으며, 부화 후 30~40일째를 거치면서 염색인기와 주변인기의 난모세포로 성장하였다. 난황은 부화 후 80일째의 자어에서 생성되기 시작하였고, 부화 후 100일째가 되어 eosin에 염색되는 난황구가 생성되었다. 이후 난모세포는 난황이 지속적으로 축적되면서 세포의 크기와 수가 증가하기 시작하였고, 부화 후 약 10개월째에는 난막과 여포세포층에 의해 둘러싸여진 난모세포로 분화하였다. 한편 정소는 부화 후 25일경 치어에서 분화되기 시작하였고, 40일경 유사분열을 통해 정원세포를 둘러싸는 포낭을 형성하였다. 부화 후 100일째가 되면 정소는 정소엽 구조를 형성하였고 hematoxylin에 매우 진하게 염색되는 정모세포로 분화하였다. 부화 후 7개월째 치어의 정소엽 내부에 정세포가 출현한 이후, 부화 후 만 1년을 경과한 치어에서 최초로 성숙한 정자가 출현하였다. 위 결과를 바탕으로 인공적으로 부화된 꼬치동자개 자치어의 성분화는 다른 종에서 보이는 것과 같이 정상적인 발달을 보인다고 판단되었다.

• 한국응용곤충학회지
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• 제46권2호
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• pp.295-302
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• 2007

천잠의 연중 실내사육법을 확립하고자 천잠의 의잠절식, 수시부화 및 최청법을 조사하였다. 천잠의 일시소잠을 위하여 의잠을 절식 실험한 결과, $25^{\circ}C$ 와 $5^{\circ}C$ 에서 1일간 보호한 4령기잠기 생존율이 각각 83.3% 및 96.0% 로 의잠 절식기간의 보호온도가 낮을수록 생존율이 높았다. 연중 다회사육을 위해 수시부화실험을 한 결과, 천잠알을 2개월 냉장할 경우에는 $5^{\circ}C$가 좋았으나 6개월 이상 냉장하여 사용할 경우에는 $2.5^{\circ}C$또는 $0^{\circ}C$에 보호하는 것이 실용부화비율이 높은 것으로 나타났다. 또한 일시부화에 적합한 천잠알의 보호조건을 조사한 결과, 관행적 최청방법 ($25^{\circ}C$ 보호)으로는 5-6일 걸리는 천잠알의 부화가 $15^{\circ}C$ 예비최청과 암최청 방법의 도입으로 2일간에 80% 가 부화하는 좋은 성적을 얻을 수 있었다.

• 한국어류학회지
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• 제35권2호
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• pp.83-90
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• 2023

전어는 부화 후 5일째 평균전장 5.96 mm로 부설골, 전액골, 전상악골, 치골이 먼저 골화하였다. 부화 후 16일째 평균전장 9.96 mm로 전이골, 후이골, 외익상골, 상설골이 골화하였다. 부화 후 25일째 평균전장 11.03 mm로 상쇄골, 후측두골이 골화하기 시작하였으며, 4개의 사출골이 골화하였다. 부화 후 28일째 평균전장 12.34 mm로 액골, 익이골, 상이골, 외후두골, 기저후두골, 안전골, 주상악골, 설악골, 전새개골, 주새개골, 하설골이 골화하였다. 부화 후 36일째 평균전장 16.11 mm로 견갑골이 골화하였고, 부화 후 37일째 평균전장 16.25 mm로 사골, 비골, 노정골, 상후두골, 안하골이 골화하였다. 부화 후 45일째 평균전장 21.14 mm로 오혜골이 골화하여 견대부의 골화가 완성되었다. 부화 후 48일째 평균전장 23.20 mm로 관절골, 하새개골이 골화하였다. 부화 후 53일째 평균전장 30.11 mm로 서골, 구개골, 내익상골, 각골, 방골, 접속골, 인설골이 골화하면서 모든 골격의 골화가 완료되었다.

• Clinical and Experimental Reproductive Medicine
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• 제43권3호
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• pp.152-156
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• 2016

Objective: We studied the effect of the site of laser zona opening on the complete hatching of mouse blastocysts and the cell numbers of the completely hatched blastocysts. Methods: Mouse blastocysts were randomly allocated to the inner cell mass (ICM) group (zona opening performed at the site of the ICM, n=125), the trophectoderm (TE) group (zona opening performed opposite to the ICM, n=125) and the control group (no zona opening, n=125). Results: The rate of complete hatching of the blastocysts was not significantly different in the ICM and the TE group (84.8% vs 80.8%, respectively; p=0.402), but was significantly lower in the control group (51.2%, p<0.001). The cell numbers in the completely hatched blastocysts were comparable in the control group, the ICM group, and the TE group ($69{\pm}19.3$, $74{\pm}15.7$, and $71{\pm}16.8$, respectively; p=0.680). Conclusion: These findings indicate that the site of laser zona opening did not influence the rate of complete hatching of mouse blastocysts or their cell numbers.

• 한국발생생물학회지:발생과생식
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• 제17권3호
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• pp.247-255
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• 2013

The gonadsomatic index (GSI) of mottled skate was the highest in April, GSI and HSI showed a reverse phase for its reproductive cycle. The fish had one pair of egg capsules, having 1 to 7 fertilized eggs, and spawned all the year round. When surveying the reproductive characteristics of females over 63 cm in disc width, we found the spawning peak was between April to June, and the appearance ratio of egg capsules was the highest in May (32.1%). The eggs were hatched at $8^{\circ}C$, $13^{\circ}C$, $18^{\circ}C$, water temperature (12.8 to $24.2^{\circ}C$), and the best hatching temperature was $18^{\circ}C$. The number of fish hatched was 4 to 5 fish/egg capsules, and the hatching rate was 100%. The sex ratios of hatching larvae were 45.5% female and 54.5% male. Therefore this study will provide fundamental data and information for artificial reproduction of the mottled skate.

• Fisheries and Aquatic Sciences
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• 제8권4호
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• pp.228-234
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• 2005

Despite the relatively high production of fingerlings of the olive flounder Paralichthys olivaceus, its larval rearing in terms of first feeding has not been fully analyzed. We evaluated the variations of amino acids and fatty acids of starved larvae over 96 hr after hatching. We also investigated depletion of the yolk and oil globule of starved larvae and those fed the rotifer Brachionus plicatilis. In addition, the optimum size of the rotifers according to the mouth size of the larvae, and the point of no return with delay of the first feeding, were also examined. The amino acids in the egg decreased abruptly during embryo development. At 48 to 72 hr after hatching, the amino acids of starved larvae decreased by $30-40\%$ from the level in newly hatched larvae. The concentrations of fatty acids in newly hatched larvae were lower than those of floating eggs and dropped sharply at 48 hr after hatching, when the yolk disappeared. The starved larvae depleted their yolksacs and oil globules earlier than the fed larvae did. At 84 hr after hatching, rotifers were detected for the first time in the guts of the larvae, which were about 3 mm in total length. The point of no return appeared to be close to the fourth day from the first feeding. For a high survival rate of P. olivaceus larvae, the first feeding should occur before the third day after hatching.

• International Journal of Industrial Entomology and Biomaterials
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• 제23권2호
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• pp.207-213
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• 2011

The diapause of $Telegryllus$ $emma$, the Emma field cricket, was investigated to study the ecological characteristics of the species. Changes in the volume, oxygen consumption, and water content of T. emma eggs were followed from oviposition. An increase in volume, oxygen consumption and water uptake occurred from 7 to 8 days following oviposition. The oxygen consumption of the eggs increased slowly for 7 days following oviposition, but then decreased until 15 days following oviposition. These results showed that a physiological change at diapause initiation affected the volume, water content, and oxygen consumption of the $T.$ $emma$ eggs. An experimental investigation of egg hatching showed that the eggs could be stocked at $10^{\circ}C$ for 40 days with a 14 day pre-period after laying and yield, 62.1% hatchability under these conditions. Maintaining the temperature at approximately $10^{\circ}C$ was favorable for hatching. Another experiment on egg hatching showed that the storage of eggs at $10^{\circ}C$ from 40 to 180 days would ensure satisfactory, hatching capacity.

• 한국패류학회지
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• 제12권1호
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• pp.47-51
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• 1996

Radix auricularia coreana, the intermediate host of Fasciola gigantica, is the most common pulmonate snail in Korea, This species is often found intermingled with Austropeplea ollula, the intermediate host of F. hepatica, in their natural habitats. In the present study. the life history of Radix auricularia coreana was examined under three different laboratory conditions. Egg-masses were taken from the field-collected adult R. auricularia coreana and incubated in the temperature ramges of 22-26$^{\circ}C$. The hatching began after 11 days from spawned eggs, and complete hatching took about 12 days. The hatching rate was about 88%. The juvenile snails were cultured at three different laboratory conditions. When the juvenile snails were cultured in the aquarium fed on lettuce leaves at 22-26$^{\circ}C$, the snails reached 20 mm in shell length at 86 days after hatching. The bottom of each aquarium was filled up with washed sand(1.5 cm) and decomposing ark shells were put on the sand. The aquarium was then filled with four litres of distilled water and continuously aerated. Most of snails (93%) survived until the experimenta period. The dggs are laid in 40 days after hatching; the averge number of eggs per egg-mass was 40.8.

• 한국수산과학회지
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• 제54권1호
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• pp.124-128
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• 2021

This study was conducted to evaluate the effects of incubation methods and transfer timings on the hatching rate of fertilized eggs of the river puffer Takifugu obscurus. Four incubation methods were tested, a) control (fertilized eggs attached to the glass plate), b) bottom (fertilized eggs spread on the bottom of the tank without any treatment), c) S-bottom (removing the stickiness of the fertilized eggs, and then spreading the eggs on the bottom of the tank), and d) incubator (removing the stickiness of the fertilized eggs, and then incubating the eggs in an incubator). Additionally, four transfer timings were tested: a) control (no transfer from the incubation tank), b) zygote (fertilized eggs transferred at the zygote stage), c) segmentation (fertilized eggs transferred at the segmentation stage), and d) pharygula (fertilized eggs transferred at the pharygula state). The results showed that the hatching rate of incubator was significantly higher than those of control, bottom, and glass (P<0.05). The results also showed that the hatching rates of control and pharygula were significantly higher than those of zygote and segmentation (P<0.05).

• 한국수산과학회지
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• 제56권1호
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• pp.44-53
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• 2023

In this study, the morphological development and early life cycle of larvae and juvenile Rhinogobius brunneus found in Wicheon, Nakdong River, Korea, were investigated. The fertilized eggs were 2.20×0.68 mm (long×short) in diameter. The eggs began hatching approximately 104 h after fertilization at water temperatures of 17.3-20.5℃ (mean 18.9±1.6℃). The newly hatched yolk-sac larvae were 3.71±0.06 mm in total length (TL), with an unopened anus. Three days after hatching, the preflexion larvae were 4.37±0.16 mm in TL with yolk absorption. Twenty days after hatching, the flexion larvae were 6.50±0.22 mm in TL and the tip of the notochord was bent upward. Twenty-seven days after hatching, the postflexion larvae were 11.8±0.63 mm in TL, and the tip of the urostyle was bent at 45°. Forty days after hatching, individuals measured 18.5±0.93 mm in TL and were considered as juveniles as the number of fins became constant for each part. All the postflexion larvae had detached fins. Additionally, the melanophore was observed to be distributed on the head, centrum of the body, and dorsal fin, and there was a difference in the morphology from the water stream.