• Environmental Analysis Health and Toxicology
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• v.16 no.2
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• pp.51-56
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• 2001

To evaluate the arsenic effect of fish endocrine disruption, crucian carp (Carassius auratus) were treated with 0.5 mg/L and 3.0 mg/L of As$_2$O$_3$ for 14 days and gonadal development was examined by histological analysis. In ovaries from female crucial carps exposed to 3.0 mg/L, immature follicles and atretic follicles were appeared while various normal developmental stages of oocytes were shown in control group. Body weight and Gonadosomatic Index (GSI) of treated carp were also decreased compared to control group. However, no other significant histological changes in liver or kidney were shown in this exposure scheme. This means that reproductive organs are more sensitive than other organs and arsenic may exert endocrine disrupting effect through inhibiting the development of reproductive organ in fish.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.08a
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• pp.42-44
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• 2001

연중 밀어 (Rhinogobiw brumeu)의 생식소 성숙을 조사하였다. 난소 및 정소의 성숙은 체장 60 mm 이상의 개체에서 뚜렷하였다. 난소는 원추형이며 정소는 쐐기모양으로 복강의 등쪽에 위치한다. 연중 성성숙지수 (gonadosomatic index)의 변화는 암컷 0.19 - 14.28 수컷 0.15-13.34로 산란시기는 5월 하순부터 6월 초순의 하계번식 어류로 사료된다. 성숙기에서 산란기에 이르는 동안 난소내 난자의 성숙정도는 불균질하며 전체 밀어 군집내에서 7월 하순까지도 성성숙지수 (GSI)가 비교적 높게 유지되는 것으로 보아 1차 산란 이후에도 소규모의 산란이 하계에 걸쳐 진행되는 것으로 사료된다. 생식소의 발달은 동계에 시작되어 난소내 난자는 춘계와 하계에 걸쳐 성장이 일어나 지름 0.5 mm의 성숙난자를 형성한다. 이 시기의 정소는 성숙한 정자가 세정관내를 가득 채우고 있다. 정자의 길이는 45 um 이며 두부의 직경은 5 um이며 미토콘드리아를 갖는 중편이 두부 기저부에 함입된 형태이며 첨체를 갖지 않는다.

• Journal of Aquaculture
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• v.14 no.2
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• pp.73-79
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• 2001

Testicular development of the male African lungfish, Protopterus annectens (Owen) was investigated histologically. The testis was found to be an elongated structure that possessed two distinct portions: an anterior spermatogenic part that was made up of a system of testicular tubules and a posterior vesicular part that invaded the kidney tissue. Spermatogenesis can be divided into five stages; primary spermatogonia, secondary spermatogonia, spermatocyte, spermatids and spermatozoa. Based on the gonadosomatic index (GSI) and histological changes observed, the reproductive cycle can be divided onto four distinct stages: resting and quiescent (December to February), growing (March to June) ripe and spent (July to August) and postspawning (September to November). The GSI was the maximum on July when reproductive cells were mature, ripe and ready for spawning; and the minimum in August after fish spawned.

• The Korean Journal of Zoology
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• v.36 no.4
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• pp.580-587
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• 1993

북방산개구리의 성체 수컷들 년중 채집하여 gonadosomatic index(GSI)와 정자형성과 정 및 정소내 testosterone양의 변화를 조사하였다 정자형성은 8월에 시작되어 9월에 가장 활발하게 진행되었으며 이때 GSI도 가장 높았고 세정관의 단면적도 가장 넓었다 번식기(2월) 이후 일정기간 동안에는(3월-7월) 정자형성이 정지되었으며, GSI나 세정관의 단면적도 최저치를 나타내었다. 정소내 testosterone양은 11월부터 급격히 증가하여 2월에 가장 높았으며 3월부터 급격히 감소되어 10월 까지 매우 낮은 농도를 유지하였다. Interstitial cell의 수도 동면기간이 찰동기 보다 훨씬 많았으며 핵의 크기도 동면기간이 훨씬 컷다. 따라서 testosterone의 생성 증가와 interstitial cell의 활성화가 일치함을 알 수 있었다. 본 결과들은 북방산개구리의 정 소에서는 정자형성과정이 불연속적으로 일어난다는 것과 2월 이후에는 testosterone의 양이 급격히 줄어드는 것으로 보아 이 개구리의 번식기가 2월임을 확인해 주고 있다.

• Development and Reproduction
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• v.25 no.3
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• pp.145-155
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• 2021

Reproductive cycle of the blue-striped angelfish, Chaetodontoplus septentrionalis were histologically investigated. Fish were monthly collected in the coastal waters of Munseom, Seogwipo, Jeju-Island from February to December 2018. The gonadosomatic index (GSI) increased from May and maintained high values in August. The reproductive cycle of female fish can be classified by the characteristics observed during gonadal development as followed: growing stage (November to June), early mature stage (May to June), mature and spawning stage (June to September), and degenerative and recovery stage (September to December). In the male, testicular development period was similar to that of ovarian development period, but mature and spawning period was one month longer from June to October. Fecundity of mature female ranged from 4,601 to 22,840 and was correlated positively with total length and body weight. The histological analysis of gonadal development indicated that the C. septentrionalis was summer-spawning type and is considered a multiple spawner during spawning season.

• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.419-424
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• 2015

In order to determine the ovarian cycle of Asian Toad, Bufo gargarizans, the developmental stage based on the gonadosomatic index (GSI), size of follicle oocytes in ovary and vitellogenesis for adult females were investigated all around the year. The weight of ovary and GSI were the lowest from April, and all follicle oocytes exist in the pre-vitellogenic form, indicating that the vitellogenesis was suspended. The follicle oocytes in early-vitellogenic stage appeared in ovary during may when the weight of ovary and GSI start to increased, and the follicle oocytes in mid-vitellogenic and pre-vitellogenic stages existed during June and the weight of ovary and GSI also increased. This indicates that vitellogenesis has been carried out actively during this period. The follicle oocytes in mid-vitellogenic stage and late-vitellogenic stage when the vitellogenesis was also completed existed on September. Post-vitellogenic follicle oocytes after vitellogenesis started to appear from October and rapidly increased from December in hibernation. The full grown follicle oocytes existed during February, indicating the ovarian cycle that all follicle oocytes in ovary are developed separately, not synchronized, during the growing period of follicle oocytes and the post-vitellogenic follicle oocytes are maintained the ovulation period.

• Korean Journal of Environment and Ecology
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• v.28 no.3
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• pp.287-292
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• 2014

In order to determine the ovarian cycle of Korean brown frog, Rana coreana, the developmental stage based on the gonadosomatic index (GSI), size of follicle oocytes in ovary and vitellogenesis for adult females were investigated all around the year. The weight of ovary and GSI were the lowest from March to May, and all follicle oocytes existed in the pre-vitellogenic form, indicating that the vitellogenesis was suspended. The follicle oocytes in early-vitellogenic stage appeared in ovary during June when the weight of ovary and GSI started to increase, and the follicle oocytes in mid-vitellogenic and pre-vitellogenic stages existed during August and the weight of ovary and GSI also increased. This indicates that vitellogenesis has been carried out actively during this period. The follicle oocytes in mid-vitellogenic stage and late-vitellogenic stage when the vitellogenesis was also completed existed between September and November. Post-vitellogenic follicle oocytes after vitellogenesis started to appear from December in hibernation, and the full grown follicle oocytes existed during February, indicating the ovarian cycle that all follicle oocytes in ovary are developed separately, not synchronized, during the growing period of follicle oocytes and the post-vitellogenic follicle oocytes are maintained the ovulation period.

• Development and Reproduction
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• v.12 no.2
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• pp.195-202
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• 2008

The gonadosomatic index, germ cell differentiation, and the ovarian cycle in female jicon scallop, Chlamys farreri were studied by histologic and cytologic observations. In the early vitellogenic oocyte, the Golgi complex, mitochondria and rough endoplasmic reticulum were involved in the formation of lipid droplets. In the late vitellogenic oocyte, exogenous substances, namely, glycogen particles and lipid granular substances appeared in the germinal epithelium passed into the ooplasm through the microvilli of the envelope. Yolk granules and multivesicular bodies were involved in the formation of proteinecious yolk granules in the late vitellogenic oocyte. Vitellogenesis occurrs by endogenous autosynthesis and exogenous heterosynthesis. The auxiliary cells function as nutritive cells in the formation and development of the previtellogenic and early vitellogenic oocytes in their earlr stages. Monthly changes in the gonadosomatic index were closely associated with ovarian developmental phases. The reproductive cycle of this species can be classified into five stages: early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to December). Spawning occurred from June to August, and the major spawning season was from July to August when the sea water was at high temperature.

• Development and Reproduction
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• v.14 no.4
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• pp.225-231
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• 2010

Gonadal development and reproductive cycles of red sea urchin Pseudocentrotus depressus were investigated based on the monthly variations of gonadosomatic index (GSI), gametogenesis and developmental phases of gonad. The specimens were sampled monthly in the north coastal waters of Ongpo and the south coastal waters Bubhwan of Jeju Island, Korea, from December 1994 to December 1995. Monthly changes of GSI values and reproductive cycles showed similar trends in Ongpo and Bubhwan. In females GSI values were reached the maximum in December ($17.8{\pm}4.04$ in Ongpo, $13.8{\pm}1.51$ in Bubhwan). In males GSI values were reached the maximum in December ($15.4{\pm}1.53$ in Ongpo, $13.6{\pm}1.32$ in Bubhwan). In both Ongpo and Bubhwan major spawning probably occurred between November and February when water temperatures and daylengths decrease. The histological observations of the gonads suggested that this species seemed to have a synchronous gametogenesis and one spawning season a year in Jeju Island costal waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.245-250
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• 2005

The maturity and spawning of Pacific cod, Gadus macrocephalus, was studied using samples caught by gillnets in the East Sea from January to December 2003. Monthly changes of maturity observed with the naked eyes for females showed that maturing Pacific cod appeared from August, and their numbers increased to $83\%\;and\;100\%$ in November and December, respectively. In January, mature and spawning Pacific cod were observed for the first time and composed over $40\%$ of the population. In February, the proportion of spawning individuals increased to over $50\%$, however, the mature individuals decreased to less than $10\%$. In March, mature fish were not found, and all were in an immature (spent) or spawning state. From April to July all fish remained in immature condition. The males maintained this trend with the females, whereas, mature males appeared from November to March. Monthly changes in the gonadosomatic index (GSI) of females and males showed higher values both in January and February and declined sharply in March. The lower value remained until October and then began to increase from November for the female population. For the males, however, this value remained lower until August, and then began to increase from September, and showed higher values in October through December than in January and February. These results indicated that the spawning season of Pacific cod was from December to March, and the main spawning season was from January to February, and the period of the spawning season was longer for males than the females. The diameter of the matured oocytes was 0.80-1.10 mm with a single mode of 0.95 mm. Fecundity was 1,300,000-9,400,000 in total length of 65-95 cm and the relationship between the total length (TL, cm) and fecundity (Fc) was Fc= $180,248\timesTL-10,883,638$. The total length at first maturity was observed at 57 cm for females and 47 cm for males. The size at $50\%$ group maturity was estimated to be 63.9 cm for females and 56.0 cm for males.