• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.198-205
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• 2011

Early life history of the endangered species, Gobiobotia macrocephala was investigated to provide baseline data for biological characteristics and recovery. Adult fish were sampled by spoon net at Hongcheon-gun, Gangwon-do, Korea in April to June 2010. The female's eggs were obtained by injecting Ovaprim and fertilized by dry method in the laboratory. The mature eggs were slightly adhesive and transparent with greyish and average 0.89${\pm}$0.04mm in diameter. The hatching of the embryo took place in about 107 hours after fertilization under water temperature of 23$^{\circ}C$ and newly hatched larvae were average 4.6${\pm}$0.16mm in total length. At 4 days after hatching, they were average 6.1${\pm}$0.20mm in total length and their yolk sacs were completely absorbed. From 15 days after hatching, they entered the juvenile stage and reached at 8.6${\pm}$0.67mm in total length. At the 100 days after hatching, their band patterns and external form were similar to those of adults, and they averaged 31.5${\pm}$3.32mm in total length.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.136-143
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• 2011

Early life history of the endangered species Gobiobotia brevibarba was investigated to provide baseline data for biological characteristics and restoration. Adult fish were sampled by spoon net capture at Hongcheon-gun, Gangwon-do, Korea, in April 2010. Eggs were obtained after injection of Ovarprim and were artificially fertilized by the dry method in the laboratory. The mature eggs were slightly adhesive and transparent with greyish and average $1.24{\pm}0.07$ mm in diameter. The hatching of the embryos took place about 120 h after fertilization at a water temperature of $23^{\circ}C$. The newly-hatched larva averaged $5.5{\pm}0.29$ mm in total length. Four days after hatching, they averaged $7.4{\pm}0.26$ mm in total length and their yolk sacs were completely absorbed. From 15 days after hatching, they entered the juvenile stage and reached $9.9{\pm}0.72$ mm in total length. One hundred days after hatching, their band patterns and external form were similar to those of adults, and they averaged $36.0{\pm}3.11$ mm in total length.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.30-38
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• 2019

Egg development and early life history of the Korean endemic sand spine loach, Cobitis nalbanti, were investigated in the present study. Adult fish were sampled using spoon nets at the Yeongsan River in Seongam-ri, Bukha-myeon, Jangseong-gun, Jeollanam-do, Korea, June 2011. Eggs were obtained after injecting Ovarprim into females. Eggs were then artificially fertilized using the dry method in the laboratory. Mature eggs were transparent and slightly adhesive with light yellowish coloring, measured $0.99{\pm}0.03mm$ ($mean{\pm}SD$) in diameter. And number of spawned eggs were $1,527{\pm}410$ per individual. Hatching (50%) of the embryo occurred 52 hours after fertilization a water temperature of $25^{\circ}C$, and the average newly hatched larvae size was about $4.2{\pm}0.22mm$ in total length. At fifth day after hatching, the larval total length reached $6.0{\pm}0.34mm$ on average and their yolk sac had been completely absorbed. At fifteen day after hatching, larva entered the juvenile stage and reached $10.8{\pm}0.45mm$ in total length. At 100th day after hatching, the formation of Gambetta's zone of four dotted line was complete and juveniles were similar in general appearance to adults, and they averaged $41.1{\pm}2.95mm$ in total length.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.157-165
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• 1987

On January 16, 1986, mature adults of smooth lumpsucker, Aptocyclus ventricosus (Pallas) were collected from the coastal water of Okkye, Myongju-gun, Kangwon-do, Korea. The authors carried out artificial insemination on the boat. The eggs were incubated and the larvae were reared in laboratory. During the incubation period water temperature fluctuated between $7.5^{\circ}C$ and $21.4^{\circ}C$. The eggs of smooth lumpsucker are demersal and adhesive. The eggs diameters were varied from 2.28 to 2.36 mm. The hatching took place in ca. 725 hours after fertilization. The newly hatched larvae were 6.0-6.9 mm in total length. The features of the hatched larvae lie in the tadpole-like body form and in the well developed sucking disk, namely the ventral fins. 17 days after hatching, the larva attained 9.1 mm in total length. The gill opening retained a small opening at its upper part. Melanophores were developed on the tail. 31 days after hatching, the larva attained 10.6 mm in total length, and became juvenile. The first dorsal fin was disappeared. 105 days after hatching, the larvae attained 15.4-17.5 mm in total length.

• Korean Journal of Ichthyology
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• v.28 no.3
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• pp.156-163
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• 2016

Egg development and early life history of Korean southern spine loach, Iksookimia hugowolfeldi, were observed in the present study. Eggs were obtained after injecting females with 0.5 mL/kg of Ovarprim. Eggs were artificially fertilized using the dry method in the laboratory. Number of spawned eggs were $1,933{\pm}530per$ individual. Mature eggs were slightly adhesive with light yellowish coloring, and they measured $1.35{\pm}0.03mm$ in diameter. Hatching of the embryo occurred 56 h (50%) after fertilization at water temperature $25^{\circ}C$, and newly hatched larvae were averaged of $5.6{\pm}0.18mm$ in total length. At 5 days after hatching, larvae averaged $7.8{\pm}0.31mm$ in total length and their yolk sacs had been completely absorbed. Beginning at 15 days after hatching, the fish entered the juvenile stage and reached $13.2{\pm}0.87mm$ in total length. At 100 days after hatching, the band patterns and external form of juvenile were similar to those of adults, and they averaged $49.2{\pm}4.29mm$ in total length.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.52-61
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• 2017

The egg development and early life history of Korean endemic fish, Squalidus multimaculatus (Gobioninae), were investigated. The eggs from the females were obtained by injecting 10 IU/g of human chorionic gonadotropin and inseminated by wet method in the laboratory. The fertilized eggs were 0.8~0.9 mm in diameter and had no oil globules. The embryo began to hatch about 65 hrs after fertilization under water temperature of $24{\pm}1^{\circ}C$. The newly-hatched larvae were 2.5~3.1 mm in total length, and their mouth and anus were not opened. Four days after hatching, the postlarva were 4.0~4.2 mm in total length, and their york sacs were completely absorbed. They entered the juvenile stage when all fin-rays were formed at 30 days after hatching, and their total length were 11.2~15.7 mm. At 45 days after hatching, the external from of juveniles were similar to those of adults (total length were 18.8~22.5 mm), and 80 days after hatching, the external characteristics from of juveniles were same to adults (total length were 25.7~35.9 mm).

• Korean Journal of Ichthyology
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• v.32 no.4
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• pp.222-231
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• 2020

The egg development and early life history of Sharpbelly Hemiculter leucisculus were investigated. For the experiments, the mature adults were collected at the Lake Yedang in Korea. The eggs from the females were obtained by injecting 10 IU/g of human chorionic gonadotropin and inseminated by wet method in the laboratory. The fertilized eggs were 0.97±0.02 mm (0.9~1.0 mm n=30) in diameter. The embryo began to hatch about 32 hrs after fertilization under water temperature of 22±1℃. The newly-hatched larvae were 3.0±0.2 mm (2.6~3.4 mm, n=15) in total length, and they haven't Melanophore. Six days after hatching, the Preflexion larva were 5.7±0.1 mm (5.4~5.8 mm, n=15) in total length, and they began to eat a Rotifer. 17 days after hatching, the Flexion larva were 6.8±0.2 mm (6.5~7.0 mm, n=15) in total length, and a gas bladder develop above the intestine. 30 days after hatching, the Postflexion larva were 8.8±0.7 mm (7.9~10.3 mm, n=15) in total length, three dorsal fin rays began to develop in the membrane fins. 50 days after hatching, the Juvenile were 20.8±0.8 mm (18.8~24.6 mm, n=15) in total length, and all their fin-rays were formed.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.75-83
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• 2018

This study is to observe species identification and early life history of Korean endemic species of Tanakia latimarginata and to use it as a basis for taxonomic studies. As a result of morphological identification, a dark band appeared at the margin of the anal fin, and the ovipositor color of the female was light orange. The shape of the egg was fusiform and sticky. The egg size (long${\times}$short diameter) averaged $4.41{\times}1.44mm$. The incubation time was 126 hours after the fertilization at an average water temperature of $21.0^{\circ}C$. Immediately after hatching, the larvae had egg yolk at an average total length of $5.91{\pm}0.18mm$ (n=5). At 18 days after hatching, the trunk fur was developed in the caudal fin with an average total length of $8.02{\pm}0.08mm$ (n=5). At 41 days after hatching, the larvae absorbed egg yolk at an average total length of $8.70{\pm}0.23mm$ (n=5). At 80 days after hatching, the average length of the fins was $12.6{\pm}0.28mm$ (n=5). The number of fin of the dorsal fin was iii.8, the anal fin iii.9~10, the caudal fin 19, lateral line scales 32~35 were similar to their brood stork.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.73-82
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• 2005

This study was conducted, based on the field survey and laboratory observations, to elucidate egg developmental processes and their characteristics of the Korean slender gudgeon, Squalidus gracilis majimae. For the experiments, the mature adults were collected at the Woongcheon-Cheon Stream and Boreung Reservoir located in Boreung City, Chungnam Province and eggs were obtained from the natural spawning area. Morphological characteristics of the egg and embryonic development were summarized as follows: The shape of the fertilized egg was spherical, adhesive and transparent. The fertilized egg was 2.9${\pm}$0.3 mm (n = 30) in mean diameter under water temperature of $26{\pm}1.5^{\circ}C$, light white in color and had no oil droplets. After 20 minutes from the time of fertilization, a blastodisc was formed and divided into two cells at 48 minutes after fertilization. The blastular stage occurred at 5 hours 40 minutes after fertilization and the gastrular stage was detected at 8 hours 41 minutes after fertilization. The beginning of embryo formation was observed at 12 hours 58 minutes after fertilization and optic vesicles and 9 somites were discovered at 17 hours 05 minutes after fertilization. Differentiation of brains and embryo wiggling were observed at 37 hours 27 minutes after fertilization. Heart beating and the formation of melanophores in optic vesicles were detected at 44 hours 46 minutes after fertilization. The formation of pectoral fins and melanophores in the body were discovered at 50 hours 36 minutes after fertilization. Hatching occurred at 57 hours 49 minutes after fertilization. The newly hatched larvae were 3.3${\pm}$0.2 mm (n = 120) in total length. We believe that these results may contribute the species and population conservations under the situation of accelerated water pollution and the decreases of its diversity.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.119-133
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• 1997

In spite of much progress in vitro fertilization and embryo transfer (IVF-ET) program, the pregnancy rate remains at 20-30%, and the endometrial implantation rate per embryo transferred at 10-15%. As a result, about 90% of embryos may fail to implant to the endometrium, and many attempts such as optimization of follicular development, improvement of in vitro culture system including coculture, and micromanipulation of zona pellucida have been made to improve embryonic implantation after IVF-ET. Recently, several procedures of assisted hatching (AH) using micromanipulation have been introduced, and pregnancies and births have been obtained after AH. To develop and establish AH as an effective procedure to improve embryonic implantation, AH with partial zona dissection (PZD) was performed in 116 cycles of 89 infertile couples who had previous repeated failures of standard IVF-ET more than two times (Group I: 71 cycles in 54 patients), or who had implantation failure of embryos with good quality (Group II: 15 cycles in 13), or who had undergone AH without specific indication (Group III: 30 cycles in 22) from January, 1995 to Februry, 1996, and the outcomes of AH were analyzed according to pregnancy rate. The number of oocytes retrieved after controlled ovarian hyperstimulation (COH) was $9.9{\pm}7.1$ in Group I, $11.5{\pm}4.5$ in Group II, and $7.9{\pm}6.4$ in Group III. The number of embryos transferred after AH was $4.7{\pm}1.8$ in Group I, $5.3{\pm}1.3$ in Group II, and $3.5{\pm}2.4$ in Group III. The mean cumulative embryo score (CES) was $56.8{\pm}30.0$ in Group I, $76.1{\pm}35.9$ in Group II, and $38.5{\pm}29.9$ in Group III. The overall clinical pregnancy rate per cycle and per patient was 12.7% (9/71) and 16.7% (9/54) in Group I, 33.3% (5/15) and 38.5% (5/13) in Group II, and 6.7% (2/30) and 9.1% (2/22) in Group III, respectively. There were significant differences in the numbers of oocytes retrieved and embryos transferred, CES, and the clinical pregnancy rate per cycle among three groups. There was a significant inverse correlation between basal serum FSH level and CES, and no pregnancy occurred in patients with CES less than 20. In conclusion, AH of human embryos with PZD prior to ET has improved the implantation and pregnancy rates in IVF-ET patients with the past history of repeated failures, especially in spite of transfer of embryos with good quality, and AH will provide a range of novel techniques which may contribute much to effective management of infertile couples.