• Applied Microscopy
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• v.28 no.2
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• pp.237-253
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• 1998

The structures of the fertilizedegg envelope in threespecies of cyprinidae, leoparddanio (Brachydanio frankei), cherry barb (Barbustitteya) and white cloudmountain fish (Tanichthys albonubes) were investigated by light and electron microscopy. The fertilized eggs of all three species have colorless, transparent, spherical and non-floted type. The egg envelopes have a single micropylewhich is thought to the pathway of sperm in the area of the animal pole. Also, an outer layersof both cherry barband white cloud mountain fish areadhesive types, but in that of leoparddanio has non-adhesivetype. In leopard danio, an outer surface ofegg envelope is covered by mushroom-likestructure, that of cherry barb is arranged by button-like structure, and that of white cloud mountain fish isarranged by rod-likestructure. Inboth leopard danioand cherrybarb, the eggenvelopes consist of three distinct layers; an outer layer, a middle layer and an inner layer, and that of white cloud mountain fish hastwo layers. An innerlayer of egg envelopein leopard danio consist of 10 layers, cherry barb has 8 layers, and white cloud mountain fish has $5\sim6$ layers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.1
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• pp.31-37
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• 2021

The mass production of fertilized eggs of the convict grouper Hyporthodus septemfasciatus was studied from 2013 to 2020 for industrial aquaculture. The experiment was divided into two groups. Group 1 broodstock was raised from wild-caught fry and used from 2013 to 2020. Group 2 broodstock was raised from artificially propagated fry and used from 2019 to 2020. Males used to collect sperm for artificial insemination weighed more than 7 kg. The effects of various hormones on artificial ovulation were investigated from 2013 onward. Among these, luteinizing hormone-releasing hormone analogue (LHRHa) at 100 ㎍/kg body weight showed the most effective results and was used for artificial egg collection from 2014 onward. In Group 1, the average total egg production per year, average egg production per individual, fertilization rate, and hatching rate were 26,143 mL, 609.7 mL, 93.3%, and 91.8%, respectively, and in Group 2, were 2,750 mL, 316.5 mL, 92.1%, and 90.4%, respectively. Based on these results, we showed that a large number of fertilized eggs for artificial seeding could be produced consistently. Moreover, the mass production of fertilized eggs in Group 2 establishes a foundation for the complete aquaculture cycle of H. septemfasciatus.

• Development and Reproduction
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• v.22 no.3
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• pp.289-295
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• 2018

Large quantity of eggs fail to be fertilized and many of fertilized eggs are unable to hatch in the eel, Anguilla japonica. Larvae of eel absorb egg yolk up to 8 days after hatching but the majority of hatched larvae die before they reach the stage of first feeding in this species. Genes of key enzymes for yolk processing (cathepsin B, D, L and lipoprotein lipase - abbreviated as ctsb, ctsd, ctsl and lpl, respectively) could be associated with egg quality. In this study, we investigated differences in the expression of these genes between floating eggs and sinking eggs, and also the relationship between the gene expressions of the enzymes and fertilization rates in the fertilized eggs obtained from artificially matured female eels. Expressions of yolk processing enzyme genes did not show significant difference between floating and sinking egg groups. Expression of ctsb decreased when fertilization rate was high. Expression of ctsd, ctsl and lpl, however, did not show any significant differences. These results suggest that ctsb expression could be an indicator of egg quality, and that some proteins prone to be digested by ctsb could be very important in the process of fertilization and normal cleavage in this species. Further study should identify these critical proteins to improve our understanding on the quality of fish eggs.

• Journal of Life Science
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• v.9 no.3
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• pp.333-340
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• 1999

The toxic effect of TBTO on Chlorella and Rotifer was observed. The value of 48hr-LC50 for Chlorella (3.3$\mu\textrm{g}$/L) estimated to be almost 500 times as high as that for Rotifer (6.7ng/L). A fertilized egg of olive flounder exposed in an embryo-formation stage was mostly influenced by TBTO toxicity when the fertilized egg at each stage until hatching was exposed to TBTO at the concentrations of 5 to 200ng/L. The values of LT50 were estimated to be 68.0, 41.0, 21.0, 13.0, 7.7 and 4.7 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively when the fertilized egg in a morula stage was exposed to TBTO, and the 48hr-LC50 was 8 ng/L. In case of TBTO treatment in an embryo-formation stage, the values of LT50 were 33.0, 12.5, 3.5, 1.3, 0.5 and 0.2 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively, and the value of 48hr-LC50 was 4ng/L. The values of LT50 were estimated to be 17.0, 11.0, 6.2, 4.0, 2.6 and 1.7 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively when the fertilized egg in a stage just before hatching was exposed to TBTO, and the 48hr-LC50 was below 1ng/L. The percentages of hatching were 46.2, 20.6, 21.9, 20.6 and 13.2% at 25, 50, 100, 250 and 500ng/L of TBTO, respectively when the fertilized egg in the stage just before hatching was exposed to TBTO and the measurement was done at second day after the completion of hatching. However no survival after the completion of hatching was found in all cases. With the treatment of 1, 5 and 10ng/L of TBTO, the percentages of hatching were 80.5, 70.0 and 44.1%, respectively. The percentages of survival until second day after the completion of hatching were 80.0, 63.3 and 9.1%, respectively. The percentages of hatching and survivability after the completion of hatching for the control were 84.5 and 82.5%, respectively.

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.278-283
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• 2010

Black plaice, Pleuronectes obscurus (Herzenstein), were collected and fertilized to observe egg development, temperature-related cleavage rates, and mitotic intervals (${\tau}_0$). Fertilized egg was demersal, adhesive, and did not contain oil globules. After 1.75 h, the blastodisc formed, and hatching took place 121 h after fertilization at $14^{\circ}C$. The hatched larvae were $3.5{\pm}0.16\;mm$ in total length. At higher temperatures, eggs developed faster and underwent further identical developmental processes. Additionally, ${\tau}_0$ and water temperature were strongly negatively correlated at all temperatures (Y=-2.6981X+98.767, $R^2$=0.9831, where Y is ${\tau}_0$, and X is temperature) for black plaice.

• Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.395-399
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• 2015

We observed seasonality and other characteristics of spawning in the greenling Hexagrammos agrammus off the coast of Tongyeong. Eleven spawning grounds were identified between November, 2013 and January, 2014. The fertilized eggs of H. agrammus were assigned to developmental stages I, II, III, and IV. Based on this classification, we showed that the spawning season extended from the end of October to mid-January. H. agrammus used diverse seaweed species attached to shallow bedrock as spawning substrata that provided good camouflage. Two to seven egg masses were fertilized around the holdfasts of individual seaweeds at depths of 1.2-4.0 m. We identified species-specific reproductive traits of H. agrammus during the spawning season, including strong parental care of the fertilized eggs.

• Development and Reproduction
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• v.18 no.1
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• pp.25-31
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• 2014

This study was investigated spawning behavior, structure of egg masses and egg development in Aplysia kurodai inhabiting the coastal waters of Jeju Island, Korea. The mating and courtship behavior of A. kurodai occurred in the form of unilateral copulating with chain formation. In chain copulation, only the first animal acted as a female; the second and succeeding animals acted as males (sperm donors) to the animals in front and as females to the animals behind. The fertilized eggs were packaged in capsules that are embedded in jelly to form a cylindrical string called an egg masses. The number of capsule per cm of the egg masses was 55 to 60 capsules and each capsule within the egg masses held 15 to 25 eggs. After spawning, the egg masses were bright yellow or orange in color. This egg masses color not changed until embryos developed into trochophore stage. Thereafter, as embryo developed from trochophore stage to veliger stage the egg masses color became brownish. The fertilized eggs were spherical, with a diameter of approximately $80{\pm}1{\mu}m$ at spawning. At 5 to 6 days after spawning, the embryo developed into trochophore stage and began to rotate within the egg capsule. In the trochophore stage, the precursor of the velum, called the prototroch or prevelum, developed. At 10 days after spawning, the prevelum is transformed into the velum, and the trochophore developed into veliger stage. Between 10 to 15 days after spawning, the veligers broke out of the egg capsule, and hatched as free-swimming larvae.

• Development and Reproduction
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• v.19 no.1
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• pp.25-31
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• 2015

We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium ($50{\times}50{\times}30cm$). Breeding water temperature was $27.5{\sim}28.5^{\circ}C$ (mean $28.0{\pm}0.05^{\circ}C$) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean $0.74{\pm}0.07mm$, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean $3.84{\pm}0.04mm$, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean $10.9{\pm}1.66mm$), and it had similar silver-colored body shape with its mother.

• Applied Microscopy
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• v.44 no.3
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• pp.96-99
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• 2014

Study on the egg envelope of an endemic Korean freshwater fish, Coreoleuciscus splendidus was carried out by light and scanning electron microscopes during its spawning season. The egg envelope on the entire egg is filled with plenty of long cylinder-like villi before and after fertilization. The fertilized eggs consist of two regions, the attaching and non-attaching parts to stick to the substrates. The villi covering the fertilized eggs have three kinds of villi in its length: 1) normal- sized villi of an average of $10.6{\mu}m$ on the non-attachment part; 2) longer and more slender villi over about $20{\mu}m$ on the attachment part, at least being two times longer than those of the non-attachment; and 3) shorter villi under about $5.0{\mu}m$ around the micropyle, with half the size of the non-attachment villi. The micropyle rotated in a counter-clockwise direction with five pieces of the ridges.

• Korean Journal of Animal Reproduction
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• v.4 no.1
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• pp.28-34
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• 1980

This experiment was carried out to study effects fo dosage and insemination interval on fertility and hatchability of whole semen and diluted semen with yolk skim milk and skim milk dilutors. The results obtained are as follows: 1. Whole semen showed higher fertility than diluted semen with yolk skim milk and skim milk dilutors. In case of diluted semen, the fertility was higher in 0.04$m\ell$ dosage than 0.02$m\ell$ and in skim milk than yolk skim milk dilutor. 2. The average fertility in inseminational intervals of 6, 5, 4 and 3 days was 52.4, 35.5, 48.7 and 44.2% in whole semen and 40.6, 17.2, 13.9 and 20.5% in 0.04$m\ell$ diluted semen with yolk skim milk dilutor. The fertility was not improved by shortening of insemination interval. 3. There was no considerable difference in hatchability of fertilized egg among the dosage of 0.02$m\ell$ of whole semen, 0.02$m\ell$ and 0.04$m\ell$ of diluted semen with yolk skim milk, and among the insemination intervals of 6, 5, 4 and 3 days. 4. Some differences in fertility among the passed days after insemination were decreased in the whole semen by shortening insemination interval from 6 and 5 days to 4 and 3days and also decreased in the diluted semen by shortening it to 3 days and by increasing dosage from 0.02$m\ell$ to 0.04$m\ell$. 5. Hatchability of fertilized egg showed no difference among the passed days during 6 days insemination interval both in the whole semen and the diluted semen. 6. The whole semen and the diluted semen with skim milk had not considerable difference in fertility among the passed days during 3 and 4 days insemination intervals, but the diluted semen with yolk skim milk had. 7. Hatchability of fertilized egg from the whole semen diluted semen with yolk skim milk and skim milk dilutors showed no difference among the passed days during 3 and 4 days insemination intervals.