• 한국발생생물학회지:발생과생식
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• 제19권4호
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• pp.209-215
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• 2015

Red spotted grouper, Epinephelus akaara is a popular aquaculture species in many Asian countries. This species is a protogynous hermaphrodite that first differentiates into female and changes to male later. Due to this reproductive characteristic, stable supply of male and female gametes is a key to the success of seed production in this species. Thus, understanding early gonadal differentiation is required to develop effective sex control techniques. Red spotted grouper were reared in indoor tanks and sampled every 5 days from 40 days post-hatch (DPH) to 130 DPH. Changes of gonadal tissues were examined and analyzed by means of histology. A pair of gonadal primordium has already existed underneath the kidney in the posterior part of the body cavity at 38 DPH when this study began. Gonadal primordia of 38, 40 DPH consisted of germ cells surrounded by a few somatic cells. The blood vessel was observed in the gonadal primordium at 45 DPH. The number of somatic cells and size of gonadal primordium increased age-dependently up to 60 DPH. Formation of ovarian cavity was obvious by two protuberant aggregations of somatic cells at 65 DPH. Completed ovarian cavity and oogonia were first observed in the gonad of one fish sample at 105 DPH. Based on these histological observations, it can be suggested that induction of primary male differentiation could be more successfully applied at around 60 DPH in this species.

• 한국패류학회지
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• 제18권2호
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• pp.83-91
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• 2002

자연산 바지락 (Ruditapes philippinarum) 개체군의 생식 주기와 수온-먹이섭이 및 절식조건에 따른 생식소 발달의 인위적 제어 결과를 조직학적 관찰에 의해 조사하였다. 곰소만 자연산 바지락 개체군의 생식소 발달에 따른 암수 개체의 생식주기는 초기활성기 (4-5월), 완숙기 (4-8월), 부분산란기 (5-10월), 퇴화 및 비활성기 (8-3월)의 연속적인 5단계로 구분할 수 있었다. 수온에 따른 생식소 발달의 인위적 제어 실험에서, 바지락은 저수온 (10$^{\circ}C$) 에 의해 억제되었다. 19$^{\circ}C$ 및 22$^{\circ}C$의 고수온에 노출시킨 실험구에서 생식소 발달은 고수온에 의해 촉진되었는데, 자연산 개체군의 것보다 약 1달 빠르게 나타났다. 고수온-먹이섭이 실험구에서, 작은개체 실험구의 생식소 발달 단계가 큰개체구 실험보다 더 빠르게 나타났으며, 저수온 (10$^{\circ}C$)의 것보다 더 빠르게 나타났다 (p=0.01). 암, 수 모든 개체들에서 고수온 (22-28$^{\circ}C$)-절식구 실험구의 생식소 발달관계가 고수온-섭이 실험구의 것들보다 더 빠른 것으로 나타났다. (paired sample t-test, p=0.004). 42일 경과 후 암컷과 수컷의 먹이섭이-고수온 실험구에서, 고수온-작은개체 실험구 조건이 큰개체의 생식소 발달보다 더 민감하게 나타났다. 그러나 저수온-수컷개체 실험구는 암컷 개체들의 실험구보다 반응이 좀 더 민감하게 나타났다. 전반적으로 고수온 실험구의 성적성숙이 저수온구보다 빠르게 나타났으며, 암수 개체 간에 유의한 차이를 보였다 (paired sample t-test, p=0.001). 42일 경과 후 절식 실험구에서, 고수온-수컷 큰개체 실험구의 생식소 발달이 고수온-암컷 큰개체 실험구의 것들보다 빠르게 나타났다. 그러나 작은 개체들의 생식소 발달 단계는 먹이섭이 실험구와 절식 실험구사이에 동일한 양상을 보였다. 산란 성기중 암수 개체들의 경우는 고수온-절식 실험구의 생식소 발달이 암컷과 수컷의 성 및 개체의 크기에 관계없이 고수온-먹이섭이 실험구의 것들보다 더 빠르게 나타났으며, 암수간 유의한 차를 보였다(paired sample t-test, p=0.004).

• 한국발생생물학회지:발생과생식
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• 제10권1호
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• pp.33-39
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• 2006

아무므불가사리의 생식소 발달과 생식주기를 밝히기 위하여 2003년 11월부터 2005년 2월까지 경상남도 고성 연안 해역에서 채집된 개체들을 대상으로 생식소 숙도지수 (GSI)의 월별변화, 생식소 발달과정 및 생식소 발달 단계별 난경 변화를 조사하였다. 생식소숙도지수의 월별 변화는 암컷과 수컷이 유사한 경향을 보였으며 암컷은 $3.88{\pm}3.04$, 수컷은 $0.87{\pm}0.57$의 값으로 3월에 연중 최대값을 가지다가 이후 서서히 감소하였다. GSI의 월별 변화와 생식소 발달의 조직학적 관찰을 근거로 생식 주기는 회복기($6{\sim}9$월), 성장기($10{\sim}1$월), 성숙기($2{\sim}3$월), 방출기($3{\sim}4$월), 퇴화 및 흡수기($4{\sim}5$월)의 연속적인 주기로 구분되었다. 아무르불가사리의 난발달 양상은 동시발달형이고 년 1회 산란하는 것으로 보인다.

• Animal cells and systems
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• 제5권1호
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• pp.37-44
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• 2001

Gonadal development, reproductive cycle, gonad index, meat weight rate, and first sexual maturity of the top shell, Omphalius rusticus were Investigated monthly by histological observations. Specimens were collected from the west coast of Korea during the period from January to December in 1999. O. rusticus is dioecious and oviparous. The gonad is widely situated on the surface of the digestive g1and located in the posterior spiral meat part in the shell. The ovary and the testis were composed of a number of oogenic follicles and several spermatogenic follicles, respectively. Ripe oocytes were approximately 120-130 $\mu$m in diameter. The meat weight rate peaked in June (27.7%), and then rapidly decreased in September (19.5%). Monthly changes in the gonad index in both sexes reached the maximum in June, and then sharply decreased in September. Percentages of first sexual maturity of female and male snails ranging from 9.0 to 9.9 mm in shell heights were 58.3% and 54.5%, respectively, and 100% in those over 11.0 mm in both sexes participated in reproduction. Reproductive cycle of this species can be categorized into five successive stages: in females, early active (October to April), late active (December to June), ripe (April to September), spawning (July to September) and recovery (September to January): in males, early active (November to March), late active (December to June), ripe (April to September), spawning (July to September) and recovery (September to December). Gonadal development, gametogenesis, reproductive cycle, and spawning were closely related to the seawater temperature.

• Fisheries and Aquatic Sciences
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• 제19권1호
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• pp.5.1-5.7
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• 2016

The study was conducted to know the cyclic changes in gonadal maturation and to investigate the developmental stages of oocytes and testicular germ cells of an air-breathing fish, Channa striata. Fish were sampled monthly from lentic and lotic environments of three geographical locations of Bangladesh from December to November and the histological analysis of their gonad was done to evaluate the objectives. The highest mean GSI was $5.95{\pm}0.20$ for female in July and $0.14{\pm}0.01$ for male also in July showing that the gonadal development reached its peak during this month. The highest mean oocyte diameter was $1257.50{\pm}24.17{\mu}m$ observed in July implying that the oocyte reached maturity in this month. Histological study of ovary revealed the evidence of early yolk granule stage and late yolk granule stage from April to July. In case of male four stages of spermatogenesis were distinguished and spermatozoa were highly abundant in June and July. So the monthly pooled values of GSI and the analysis of gonadal histology indicated that the peak breeding season of C. striata occurred in July in the lentic and lotic environments. Samples collected from lentic and lotic habitats are suggestive of no difference in the development of the gonad. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. striata in its natural habitat.

• 한국수산과학회지
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• 제36권4호
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• pp.352-357
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• 2003

Gonadal development and gametogenic cycle of the equilateral venus, Gomphina collected in the coastal waters of Gangneung, Gangwon-do, Korea were investigated by means of histological method from March 2001 to February 2002. Sex of the clam was dioecious. The gonads are composed of a number of gametogenic follicles. The gonad index (GI) was reached the maximum in June (3.87), and the minimum in August (0.66). The condition index (CI) was reached the maximum in May (0.051), and the minimum in January (0.028). The gametogenic cycle of the clam could be divided into five stages inactive (September to November), early active (November to March), late active (April to May), ripe (June and July) and spent/degenerative stage (July to August). Sex ratio (male/female) was 1:0.9.

• 한국발생생물학회지:발생과생식
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• 제25권3호
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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.

• 한국발생생물학회지:발생과생식
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• 제17권2호
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• pp.111-119
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• 2013

Golden hamsters reproduce in a limited time of a year. Their sexual activities are active in summer but inactive in winter during which day length does not exceed night time and environmental conditions are severe to them. The reproductive activities are determined by the length of light in a day (photoperiod). Melatonin is synthesized and secreted only at night time from the pineal gland. Duration of elevated melatonin is longer in winter than summer, resulting in gonadal regression. The present study aimed at the influences of continuous melatonin treatments impinging on the gonadal function in male golden hamsters. Animals received empty or melatonin-filled capsules for 10 weeks. They were divided into long photoperiod (LP) and short photoperiod (SP). All the animals maintained in LP (either empty or melatonin-filled capsules) showed large testes, implying that melatonin had no effects on testicular functions. Animals housed in SP displayed completely regressed testes. But animals kept in SP and implanted with melatonin capsules exhibited blockage of full regression by SP. These results suggest that constant release of melatonin prohibits the regressing influence of SP.

• 한국발생생물학회지:발생과생식
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• 제19권1호
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• pp.33-41
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• 2015

The gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-$17{\beta}$ of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-$17{\beta}$ were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.

• Animal cells and systems
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• 제6권1호
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• pp.75-80
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• 2002

A study on the effects of bisphenol A (BPA) on sex differentiation and gonadal development in medaka, Oryzias latipes, was investigated by histological examination. The fish were exposed to aqueous solutions of BPA at nominal concentrations of 50, 100, and 200 $\mu\textrm{g}$/L from newly-hatched larvae stage to 70 d. The ovaries of female fish were composed of oocytes at the chromatin nucleolus and peri-nucleolus stages at 20 d after the exposure. The testes contained a number of spermatogonia and spermatocytes at 30 d. In the process of sex differentiation. gonadal development was not different in all experimental groups until 30 d after the exposure. At 70 d after the exposure, however, advanced development of oocytes in the ovary and inhibition of spermatogenesis in the testis were observed in the BPA-treated groups compared to the non-treated controls. More females than males were identified in the 50 and 100 $\mu\textrm{g}$/L BPA-treated groups, in comparison to the 200 $\mu\textrm{g}$/L BPA-treated group and non-treated controls. Medaka exposed to 200 $\mu\textrm{g}$/L BPA were bigger compared to other experimental groups. The present study suggests that BPA may lead to problems in either mating or sexual behavior due to the difference in growth and disparity of sexual maturation between male and female fish.