• The Korean Journal of Malacology
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• v.14 no.2
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• pp.91-102
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• 1998

새꼬막은 자웅이체로서 난생이었다. 생식소는 내장낭의 간중장선에서부터 족부까지 외측의 대부분을 싸고 있으며, 난소는 난자형성소낭, 정소는 정자형성소낭으로 구성되어 있었다. 완숙란의 세포질에는 많은 난황과립을 축적하고 있으며, 난막의 외측은 얇은 젤라틴상의 피막으로 싸여 있었다. 정자형성소낭벽에는 정원, 정모, 정세포 및 변태한 정자 순으로, 소낭의 내강을 향하여 충상배열을 하며 성숙 발달되었다. 생식주기는 초기 활성기(11-5월), 후기 활성기(5-7월), 완숙기(6-9월), 부분 방출기(7-9월), 방출 및 비활성기(9-4월)로 구분할 수 있었다. 방란, 방정은 수온이 21$^{\circ}C$ 이상으로 상승하는 7월초순부터 9월까지 지속되며, 산란 최성기는 8월이었다. 비만도지수의 월별 변화는 생식주기와 아주 밀접ㅎ나 관계가 있었다. 난자형성소낭과 정자형성소낭에는 eosin에 강하게 염색되는 과립세포와 간충직들이 나타나는데, 이들은 생식소 및 생식세포형성과 발달에 영양을 공급하는 영양세포로 생각되었다.

• The Korean Journal of Malacology
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• v.14 no.1
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• pp.1-8
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• 1998

자웅이체인 배벌레(shipworm), Zachsia zenkewitschi의 생식에 관하여 연구를 진행하였다. 자성 생식기관은 하나의 난소와 소형의 웅성을 안고 있는 한 쌍의 외투막 주머니로 구성되어 있었다. 소형 웅성의 정소는 내장 신경절 주위에 위치하였다. 성숙된 알의 지름은 60$\mu\textrm{m}$이고 난황과 젤리막으로 싸여 있었다. Zachsia zenkewitschi의 정자는 약 2.6$\mu\textrm{m}$의 원추상 두부, 0.5$\mu\textrm{m}$의 첨체, 직경 약 0.9 $\mu\textrm{m}$의 중부로 되어 있었다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.599-607
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• 1998

To clarify annual reproductive cycle of Korean dark sleeper, Odontobutis platycephala (Iwata et Jeon), we examined the seasonal changes of gonadosomatic index (GSI), the proportional frequency of oocyte development stages in the ovary and the changes of sex steroid hormone levels in blood from December 1995 to November 1997. In July and August, GSI was 0.35 to 0.72 and most oocytes in the ovary were chromatin-nucleolus stage and perinucleolar stage (proportional frequency: $87\%\~96\%$). In September, GSI was 1.20 $\pm$ 0.12, some oocytes in the ovary were yolk vesifle stage (proportional frequency: $22.8\%$) and vitellogenic stage which appeared very rarely(proportional frequency: $2.2\%$). GSI increased gradually from October and reached 4.59± 0.61 to December. During this period, oocytes of vitellogenic stage increased slightly (proportional frequency in December: $22.1\%$). In January, GSI was 4.32 $\pm$ 0.72 but the proportional frequency of oocytes in vitellogenic stage increased (proportional frequency: $51.2\%$). from February, GSI was increased sharply and reached to 10.51 $\pm$ 1.04 in March, the highest value throughout the year and the proportional frequency of oocytes in vitellogenic stage also reached the highest levels (proportional frequency: $60\%$). From April, GSI was gradually decreased and fell down to 1.11 $\pm$ 0.35 in June. During this period, the proportional frequency of mature oocytes was the highest in April (proportional frequency of mature oocyte stage: $40\%$ in April, $12\%$ May, $5\%$ June) throughout the year, and atretic ovarian follicles were appeared. The blood level of estradiol-17$\beta$ ($E_2$), which stimulates the hepatic synthesis and secretion of vitellogenin, was $0.84{\pm}0.20\;ng/m{\ell}$ in August, and thereafter was not changed until December. from January, it increased sharply and reached the highest level of $ 2.85{\pm}0.35\;ng/m{\ell}$ in March throughout the year, but fell to $0.14{\pm}0.02\;ng/m{\ell}$ in July(P<0.05), 17$\alpha$-hydroxprogesterone(17$\alpha$-OHP) was the peak $13.37{\pm}0.52ng/m{\ell}$ in March, but no significant changes in other period(below $3ng/m{\ell}$, P<0.05). 17$\alpha$, 20$\beta$-dihydroxy-4-pregnen-3-one(17$\alpha$, 20$\beta$-P), which was known as the final maturation inducing hormone in teleost, was $0.74{\pm}0.09ng/m{\ell}$ in April and $0.54{\pm}0.07ng/m{\ell}$ in May, but no significant changes in other period (below $0.26\;ng/m{\ell}$, p<0.05). Taken together these results, the annual reproductive cycle of O. platycephala divided into 4 periods as follows: 1) ripe and spawning period from April to June, main spawning period was from April to May, 2) Resting period from July to August, 3) Growing period from September to December, 4) Maturing period from January to March. Moreover, It was showed that the changes of sex steroid hormone in blood played a important roles in the annual reproductive cycle of O. platycephala.

• Development and Reproduction
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• v.4 no.2
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• pp.187-193
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• 2000

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$\pm$1.5) and January (14.8$\pm$3.5), and then decreased sharply in February (2.6$\pm$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 $\beta$ level increased from November, and reached the highest value in December (1,152.3$\pm$107.2 pg/ml) and January (1,315.4$\pm$99.5 pg/ml), after then decreased in February (P<0.05). The concentration of plasma 17 $\alpha$ ,20 $\beta$-dihydroxy-4-pregnen-3-one was not significantly changed at low levels (86.6$\pm$6.5∼93.8$\pm$2.8 pg/ml) during the experimental period (P<0.05). All the fish with fully-grown oocytes in the ovary were matured and ovulated by HCG injection. The number of floating eggs were 325,000$\pm$26,000 at HCG 1,000 luhg and 195,000$\pm$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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.253-261
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• 1985

The reproduction of marbled sole Limanda yokohamae, caught near around the southeastern coast of Korea, from December 1983 to November 1984, was investigated based on such annual variations as gonadosomatic index(GSL), gametogenesis, reproductive cycle, spawning number, hepatosomatic index (HSI), and fatness. GSI began to increase in the autumn season with the onset of shorter day length and colder water temperature, and reached the maximum value in December with the shortest day length and the lowest temperature over the year. The gonad activated the proliferation of oogonia and spermatogonia in June, reached the mature stage in October, ripe in December, and spawning from the end of December to January. After spawning, it showed the resting stage which gonad remained regressive and suppressive from February to May. In addition, the adult individuals observed discharged eggs only once during their spawning period. At yolk globular stage, the substance of vitellogenin synthesized from the liver was considered to participate in the active yolk accumulation of oocytes. Marbled sole was concluded to be a typical winter spawning species in that such environmental factors as short day length and low water temperature were closely related with the gametogenesis, the stimulation of oocyte maturation, and were also affecting the ovulation.

• Korean Journal of Ichthyology
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• v.33 no.4
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• pp.252-261
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• 2021

The egg development and early life history of short barbel gudgeon Squalidus japonicus coreanus were investigated. For the experiments, the mature adults were collected at the stream Jicheon in Korea. The eggs from the females were obtain by injecting 10 IU/g of human chorionic gonadotropin and inseminated by wet method in the laboratory. The fertilized eggs were 1.12±0.03 mm (1.10~1.16 mm, n=30) in diameter. The embryo began to hatch about 49 hrs after fertilization under water temperature of 23±1℃. The newly-hatched larvae (Yolksac larva) were 3.7±0.1 mm (3.4~3.8 mm, n=16) in total length, and they haven't Melanophore. 5 days after hatching, the Preflexion larva were 5.3±0.2 mm (5.0~5.5 mm, n=16) in total length, and they began to eat a Rotifer. 19 days after hathing, the Flexion larva were 6.0±0.3 mm (5.4~6.5 mm, n=16) in total length, and they began to eat a Brine shrimp. 29 days after hatching, the Postflexion larva were 9.6±0.5 mm (8.3~10.5 mm, n=16) in total length, and dorsal fin rays are were formed. 44 days after hatching, the juvenile were 15.5±1.0 mm (13.5~17.0 mm, n=16) in total length, and all their fin-rays were formed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.368-374
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• 1986

Liparis ingens (Gilbert et Burke) is a demersal fish belonging to Liparidae, widely distributed in the coastal waters of the east coast of Korea. On January 16, 1986, mature adults of Liparis ingens were captured by a demersal gill net near Chongdongchin-ri, Kangwon-do, Korea. The authors stripped eggs and milt, and fertilized on the ship. The eggs were incubated and the larvae were reared in laboratory. The eggs of this species are demersal and adhesive, and are pale yellow, containing many oil globules. Egg diameters were varied from 1.55 to 1.65 mm. The hatching took place in ca. 747 hours after fertilization at the water temperature of $7.09{\sim}10.99^{\circ}C$ and salinity $30.62{\sim}33.98\%0$. The newly hatched larvae were elongate in shape and $4.40{\sim}4.85mm$ in total length with $12{\sim}13$ (abdominal)+40(caudal)=$52{\sim}53$ myomeres. Many melanophores were distributed on the lower jaw, pectoral fins, yolk sac, and ventral line of the tail part. Three days after hatching, the larvae reached 5.15 to 5.25 mm in total length, and the yolk sac was almost absorbed. Some melanophores appeared on the back of auditory vesicles. Seven days after hatching, the larvae attained $5.75{\sim}5.85mm$ in total length.

• Korean Journal of Ichthyology
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• v.20 no.4
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• pp.255-262
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• 2008

The endemic Korean stumpy bullhead Pseudobagrus brevicorpus is a first-grade endangered wild fish as designated by the Ministry of Environment of Korea. As part of its restoration and proliferation effort, a histological study of this fish was carried out to investigate sex differentiation and gonadal development based on F1 generation individuals obtained by artificial breeding. On days 4~5 after hatching, a pair of genital ridges including clusters of primordial germ cells was observed between the gut and the mesonephric duct. On days 20 after hatching, the ovary began to initially differentiate and contained early oocytes with chromatin-nucleolus and peri-nucleolus stages on days 30~40 after hatching. As yolk material accumulated after day 80 from hatching, the oocytes grew increasingly large and were surrounded by a distinct follicular layer. On days 306 after hatching, the oocytes grew toward a mature ovum. In the males, the testis was distinguished by emergence of spermatogonium cells on 25 days after hatching, and day 40 after hatching it contained a small number of seminal lobes forming cysts. From 173 days after hatching, the testis consisted of numerous enlarged seminal lobes including spermatocytes and spermatids. Over 14 months after hatching, some seminal lumens were filled with spermatozoa.

• Korean Journal of Ichthyology
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• v.26 no.2
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• pp.89-98
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• 2014

Eggs development and early life history of the endangered Korean dwarf loach, Kichulchoia brevifasciata (Teleostei: Cobitidae) was investigated to provide basic information regarding biological characteristics and restoration. Adult fish specimens were sampled using a spoon net at Geurnsan-myeon, Goheung-gun, Jeollanam-do, Korea from June to July 2011. Since, spawning characteristics were analyzed, and females were induced to spawn by injecting Ovaprim (0.5 mL/kg) and their eggs were artificially fertilized with sperms by the dry method in the laboratory. Total length of mature female were 46~76 mm with GSI $9.6{\pm}3.77%$, and total length of mature male was 42~52 mm with GSI $3.5{\pm}1.04%$. Sex ratio (♂/♀) was 0.10, and there were no secondary sexual characteristics. The number of mature eggs was averaged $60{\pm}28.7$ per female. The lemon yellow eggs were slightly adhesive $1.46{\pm}0.07mm$ in diameter. The embryo hatched approximately 66 h after fertilization at $25^{\circ}C$, and the hatched larvae were averaged $5.5{\pm}0.07mm$ in total length (TL). At 6 days after hatching, the larvae averaged $9.0{\pm}0.29mm$(TL) and their yolk sac was completely absorbed. At 17 days after hatching, they entered the juvenile stage and reached $12.6{\pm}0.24mm$ (TL). At 80 days after hatching, the band patterns and external form of the juveniles were similar to those of adults, and they averaged $33.0{\pm}2.19mm$(TL).