• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.1-11
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• 2006

The gonadosomatic index (GSI), oogenesis and reproductive cycle in female Neptunea (Barbitonia) afhritica cumingii were investigated by light and electron microscope observations. In the early vitellogenic oocyte, the Golgi complex and mitochondria were involved in the formation of glycogen, lipid droplets and yolk granules. Late in the vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in cytoplasm. In particular, compared with the results of other gastropods, it showed a different result that appearances of cortical granules at the cortical layer and microvilli on the vitelline envelope, which is associated with heterosynthetic vitellogenesis, were not observed in vitellogenic oocytes during oogenesis. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting membrane. Monthly changes in the gonadosomatic index in females studied in 2004 and 2005 were closely associated with ovarian developmental phases. Spawning occurred between May and August in 2004 and 2005 and the main spawning occurred between June and July when the seawater temperature rose to approximately $18-23^{\circ}C$. The female reproductive cycle can be classified into five successive stages: early active stage (September to October), late active stage (November to February), ripe stage (February to June), partially spawned stage (May to August), and recovery stage (June to August).

• Clinical and Experimental Reproductive Medicine
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• v.39 no.3
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• pp.114-117
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• 2012

Objective: It is well known that fresh blastocyst transfer results in better pregnancy outcomes with a smaller number of transferred embryos compared with cleavage stage embryo transfer. However, in terms of frozen-thawed blastocyst transfer, only a few studies are available. We aimed to evaluate clinical outcomes of frozen-thawed embryo transfer (FET) with blastocysts. Methods: Retrospective analysis of FET cycles with blastocysts (B-FET) between Jan 2007 and June 2009 was performed. Age-matched FET cycles with cleavage stage embryos (C-FET) during the same period were collected as controls. A total of 58 B-FET cycles were compared with 172 C-FET cycles and also compared with those of post-thaw extended culture blastocysts from frozen pronuclear stage embryos (22 cycles). Results: There was no difference in the patient characteristics of each group. The embryos' survival rates after thawing were comparable (>90%) and there was no difference in the implantation rate or clinical and ongoing pregnancy rate among the three groups. Conclusion: In FET, blastocyst transfers may not present better pregnancy outcomes than cleavage stage embryo transfers. A further large-scale prospective study is needed.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.60-60
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• 2003

Embryonic stem (ES) cells have property of self-renewal and can differentiate into the cells of all three primary germ layers. Recently, many growth factors, alteration of culture condition and gene modifications have been used to differentiate mouse and human ES cells into specific cell types. This study was performed to evaluate the differentiation protocol for human ES cells to the endodermal lineage cells. Human ES cells (Miz-hESl ) were cultured on STO feeder layer mitotically inactivated with mitemycin C, and embryoid bodies (EBs) were formed by suspension culture. Differentiation protocol of EBs consisted of three steps: stage I, culture of EBs for 6 days with ITSFn medium; stage II, culture of stage I cells for 8 days with N2 medium ; stage III, culture of stage II cells for 22 days with N2 medium. mRNA levels of the endodermal lineage differentiation genes were analyzed by semi- quantitative RT-PCR. The Oct-4 expression, a marker of the pluripotent state, was detected in undifferentiated human ES cells but progressively decreased after EBs formation. Differentiating human ES cells expressed marker genes of endodermal differentiation and pancreatic islet cells. GATA4, a-fetoprotein, Glut-2, and Ngn3 were expressed in all stages. However, albumin and insulin were expressed in only stage III cells. The human ES cells can be differentiated into endodermal lineage cells by multiple step culture system using various supplements. We are developing the more effective protocols for guided differentiation of human ES cells.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.393-399
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• 2004

Annual reproductive cycle of Siganus canaliculatus was studied based on monthly variation of gonadosomatic index (GSI) and histological changes of gonads. Samples were monthly collected by a set net along the southern coast of Jeju Island, Korea from January to December, 1996. Variation of the monthly mean GSI values showed similar trends in female and male. The GSI values increased from June and reached a peak in the spawning season in July $(9.65{\pm}1.96\;in\;females,\;10.00{\pm}4.27\;in\;males)$, and decreased rapidly thereafter. Female hepatosomatic index (HSI) values ranged from $1.26{\pm}0.22\;(in\;April)\;to\;2.34{\pm}0.39$ (in July), and male HSI values ranged from $1.27{\pm}0.21\;(in\;April)\;to\;1.87{\pm}0.30$ (in October). Annual reproductive cycle was classified into the following successive stages: in female, growing stage (from February to June), mature stage (from June to July), ripe and spawning stage (from July to August), recovery stage (from August to March); and in male, growing stage (from January to June), mature stage (from June to July), ripe and spent stage (from July to August), and recovery stage (from August to April). Based on these data, this species has a group-synchronous oocyte development and one spawning season a year.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.62-70
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• 2000

Annual reproductive cycle of the file fish, Stephanolepis cirrhifer (Temminck et Schlegel), was histologically investigated. Samples were collected monthly in the coastal waters of Chungmun, south of Cheju Island, Korea from July 1997 to June 1999. In males and females of S. cirrhifer, the values of GSI (gonadosomatic index) were similar to the changes of water temperature and day length. GSI values in males and females were reached the maximum in June. Reproductive cycle could be divided into the following successive stages: in females, growing stage (February to May), mature stage (May to June), spawning stage (June to August), degenerative and resting stage (September to December), and in males, growing stage (February to April), mature stage (May to June), spent stage (June to August), degenerative and resting stage (September to January), respectively. Throughout histological observation of the ovary in the spawning period, the species belong to an asynchronous and multiple spawner.

• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.201-209
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• 2001

Annual reproductive cycle of seabass, Lateolabrax japonicus, was histologically investigated based on samples captured on the coast of the Tongyoung, South Korea. The gonadosomatic index (GSI) of females began to increase in October and reached its maximum in February. The GSI of males reached its maximum in December. The change of GSI and gonadal tissue showed that the annual reproductive cycle was classified into the following successive four stages: (1) the degenerative and resting stage from March to August, (2) the growth stage from September to November, (3) the mature stage from November to December, and (4) the ripe and spawning stage from December to March.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.3
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• pp.217-226
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• 2012

Reproductive ecology of the sharp toothed eel, Muraenesox cinereus was investigated based on the samples captured in southern Korean waters from January 2010 to December 2011. Gonadosomatic index began to increase in April, and reached maximum between July to August. After spawning it began to decrease from October. Reproductive season was estimated to April-September, with peak in July. Fecundity was proportional to the size of the female, with the clutch size varying from 56,000 eggs in the smallest female (anal length, 27.0cm) to 1,400,000 eggs in the largest (anal length, 49.5cm). Size at 50% sexual maturity ($AL_{50}$), determined from mature females, were 21.9cm. Annual reproductive cycles of this species could be divided into four successive stages; immature stage (October-February), maturing stage (March-May), mature stage (June-August) and spent stage (August-October).

• Reproductive and Developmental Biology
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• v.28 no.1
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• pp.53-57
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• 2004

The study was carried out to investigate the effects of morphology, reproductive cycle, incubation time and activation of oocytes on in vitro maturation of cat oocytes and development of IVM/IVF embryos. The results were summarized as follows: 1. When recovered from ovaries collected at different stages of the reproductive cycle (inactive, follicular and luteal stage), the developmental rates of oocytes to GV and MI stage were 72.5% and 27.5%, 57.5% and 7.5%, 62.5% and 17.5%, respectively. 2. The developmental rates of oocytes with cumulus cells to GV and MI stage in different conditions of incubation (5% $CO_2$ , 95% $O_2$ and 10% $CO_2$, 90% $O_2$) were 70.0% and 27.5%, 52.5% and 20.0%, 55.0% and 12.5%, respectively. 3. The developmental rates to GV and MI oocytes when cultured at different time of incubation (17∼20, 21∼24, 25∼28 and 29∼32 h) were 67.5% and 20.0%, 67.5% and 30.0%, 62.5% and 22.5%, 65.0% and 15.0%, respectively. 4. The fertilization and cleavage rates of freshly collected oocytes with and without cumulus cells were 72.5% and 25.0%, 37.5% and 7.5%, respectively. The rates were greater in oocytes with cumulus cells than those without cumulus cells. 5. The fertilization and cleavage rates of oocytes recovered from ovaries collected at different stages of the reproductive cycle (inactive, follicular and luteal stage) were 75.0% and 25.0%, 40.0% and 7.5%, 50.0% and 15.0%, respectively.

• The Korean Journal of Malacology
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• v.16 no.1_2
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• pp.35-41
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• 2000

We investigated the gonad index (GI), gonadal development, the reprodutive cycle and first sexual maturity of the venus clam, Cyclina sinensis by histological observation. Samples were collected from the intertidal zone of Komso Bay, Chollabuk-do, west coast of Korea, from April 1998 to March 1999. This clam is dioecious and oviparous. Monthly changes in the gonad index (GI) showed a similar pattern to the reproductive cycle. Ripe oocytes are about 90-100 ㎛ in diameter. The spawning period was between early July to September, and the main spawning occurred between July and August when the sea water temperature was over 20$\^{C}$ The reproductive cycle of this species can be divided into five successive stages: early active stage (February to April), late active stage (March to June), ripe stage (April to August), partially spawned stage (July to October), and spent / inactive stage (September to February). Percentages of first sexual maturity of female and male clams measuring 26.1-30.0 ㎜ in shell length were 53.3% and 62.5%, respectively, and 100% for the clams > 41.0 ㎜. It is assumed that both sexes begin reproduction at about two years age.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.656-660
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• 2001

Gametogenesis, the reproductive cycle, and the condition index of the soft clam, Mya arenaria were investigated monthly based on histological observation at Sachon Bay, south coast of Korea from May 1998 to September 1999 . M. arenaria is dioceious. The ovary and testis were composed of a number of ovarian sacs and testicular tubules, respectively. Ripe oocytes were characterized by germinal vesicles with nucleoli, and their sizes about $60{\mu}m$ in diameter. Monthly changes in condition index and water temperature were closely related to the annual reproductive cycle. The reproductive cycle can be classified into 5 stages: early active stage (february to March), late active stage (April to August), ripe stage (September), partially spawned and spent stage (September to October), inactive stage (November and January).