• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.44-50
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• 1996

Sex differentiation in the rockfish, Sebastes schlegeli, was studied by using a histological method for the appearance of primordial germ cell, formation of primitive gonad and differentiation of female and male. The primordial germ cells were buried under fibrous mesenchymal tissue between gut and mesonephric duct of pre-larva with a total length (TL) of 6.3 mm at 2 days after parturition. In juvenile of TL $5.2\~5.9cm$ at 65 days after parturition, the gonad composed of a large number of genial cell and formed of cavity along the lateral side of the gonad, differentiated to the ovary. At this time, the gonad formed seminiferous tubules by somatic cells, differentiated to the testis. In juvenile of TL $7.0\~7.2cm$ cm at 115 days after parturition, gonads divided into testis contained pigment cell and ovary absent pigment cell. S. schlegeli differentiated directly into male or female without an intermediate female phase at early indifferentiated stage. Therefore, S. schlegeli belongs to the differentiated type of gonochoristic teleosts. At 350 days after parturition, sex ratio was approximately 1 : 1(p>0.05).

• Journal of Aquaculture
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• v.21 no.4
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• pp.252-258
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• 2008

Gonadal development and reproductive cycle of the ark shell Scarpharca subcrenata were investigated by histological observations. Samples were collected monthly from March 2007 to February 2008 in the Yeoja Bay, Yeosu, Jeollanam-do, Korea. S. subcrenata was dioecious. The gonads consist of a number of oogenic follicle and acinus. Monthly changes in the gonad index reached a maximum in June and a minimum in September. Monthly changes in the condition index reached a maximum in April and a minimum in September. The reproductive cycle of this species can be divided into five successive stages: early active stage (January to April), late active stage (March to June), ripe stage (May to August), spent stage (July to September) and recovery and resting stage (September to March). The main spawning of S. subcrenata occurred in July and August in Yeoja Bay. The sex ratio of female to male was not significantly different from 1:1.

• Journal of Aquaculture
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• v.22 no.1
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• pp.34-41
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• 2009

Gonadal development and reproductive cycle of the granular ark Tegillarca granosa were investigated by histological observations. Samples were collected monthly from January to Decemberry 2002 in the Yeoja Bay of Yeosu, Jeollanam-do, Korea. T. granosa was dioecious. The gonads consist of a number of oogenic follicle and acinus. Monthly changes in the gonad index reached a maximum in June and a minimum in August. Monthly changes in the condition index reached a maximum in July and a minimum in September. The reproductive cycle of this species can be divided into five successive stages: early active stage (March to May), late active stage (April to June), ripe stage (May to July), spent stage (July to August) and recovery and resting stage (September to March). The spawning of T. granosa occurred in July and August in Yeoja Bay. The sex ratio of female to male was not significantly different from 1:1.

• Environmental Analysis Health and Toxicology
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• v.17 no.1
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• pp.7-11
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• 2002

Effects of nonylphenol (NP) on gonadal development and growth of olive flounder, Paralichthys olivaceus were investigated. NP treatment was carried out to fry fish (during 55 to 64 days after hatching) using oral adminstration at nominal NP concentrations of 50, 100 and 150 tig/g BW Gonad before NP treatment was sexually undifferentiated as observed with mostly gonia cells. At 159 days after hatching, ovarian lamella of ovary were filled with oogonia and perinucleolus oocytes. On the other hand, testicular lobules of the testis were occupied by spermatogonia, spermatocytes and spermatids. Histological observation of ovary and testis development was any different between the control and NP treated groups. However, growth was significantly increased in NP treated groups than control groups (P< 0.05). These results considerate that NP has any effect for sex differentiation and gonadal development, but act for early growth in olive flounder.

• Development and Reproduction
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• v.11 no.3
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• pp.155-165
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• 2007

Gonad index (GI), conditon index, the reproductive cycle with gonadal development of the Neptunea (Barbitonia) arthritica cumingii, were investigated histologically, based on the samples which have been collected from the subtidal zone of Oeyeondo, Boryeong, Korea from January to December, 2006. Neptunea (Barbitonia) arthritica cumingii is dioecious and oviparous. Monthly changes in the gonad index (GI), studied for determination of spawning period, were closely associated with gonad developmental phases. The GI reached a maximum in April, and gradually decreased from May to August due to spawning. The gonadsomatic index and condition index showed similar patterns to gonad developmental phases and the spawning period. The reproductive cycle according to gonad developmental phases of this species can be classified into five successive stages in females and males: in females, 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); in males, the early active stage (September to October), late active stage (November to February), ripe stage (February to June), copulation (April to July), and recovery stage (July to August). Spawning occurred between May to August in females and April to July in males, and spawning peak in females was observed between June and July when the seawater temperature rose to above $19^{\circ}C$. Percentages of first sexual maturity of female and male snails ranging from $50.1{\sim}60.0\;mm$ in shell height were over 50%, and 100% for snails over 60.1 mm in shell height. The sex ratios of females to males were not significantly different from a 1:1 sex ratio.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2005.11a
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• pp.64-65
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• 2005

Members of the Pumilio are the RNA binding proteins acting as translational repressors and required for germ cell development and asymmetric division. We identified chicken Pum1 and Pum2 that are similar to mouse and human in highly conserved C-terminal RNA-binding domain and eight tandem repeats. The comparative sequence analysis of Pum1 and Pum2 from fly, chicken, mouse and human shows high degree of evolutionary conservation in the homology of the peptide sequence and the structure of PUM-HD (Pumilio homology domain) with similar spacing between adjacent Pum repeats. Also, structures of chicken Pum1 and Pum2 genes are almost identical to those of mouse and human. We revealed that the expression levels of Pum1 and Pum2 were the highest in hatched female gonad among various embryonic tissues, and Pum2 expressed highly in 12-day and hatched gonad by real-time RT-PCR. These results suggest that Pum1 and Pum2 might have an effect on the development of chicken gonad.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.253-262
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• 1990

Hardened seed oysters which inhabit the Hansan Bay of Korea and Hiroshima Bay of Japan were cultured at the oyster farm of Nino island near Hiroshima from June, 1972. to June, 1973. The present experiment investigated monthly increment of shell height, shell length, meat weight, moisture, fatness and gonad development of the seed oysters. Environmental factors were also checked to know ecology of the oysters. The oyster farm of Nino island near Hiroshima city showed high water temperautre and low salinity com-paring with the oyster farm of Hansan Bay. Korea. Shell height and shell ten求h of the hardened seed oyster of Hansan Bay grew faster than those of Hiroshima Bay, especially in oyster meat weight. Histological observation on gonads showed little difference in developmental process between the two localities from June through December, 1972, whereas the hardened seed oyster from Hansan Bay has grown rapidly in the development of gonad after February, 1973. It can be concluded that in the viewpoint of seed oysters productivity the hardened seed oyster from Hansan Bay is more effective than that of Hiroshima Bay comparing in seed growth, fatness and developmental process of gonad.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.208-218
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• 2001

We have investigated the gonad index (GI), gonadal development, reproductive cycle, first sexual maturity, sex ratio, the number of spawned eggs and spawning frequency of the Manila clam, Ruditapes philippinarum. Samples were collected from the intertidal zone of Komso Bay, Korea from January to December in 1999. Monthly changes in the gonad index (GI) and condition index showed a similar pattern in the reproductive cycle. The spawning period was once a year between early June and early October, there was a spawning peak between July and August when seawater temperature was over $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (June to October), and spent/inactive stage (August to March). Percentages of first sexual maturity of female and male clams of l5.1-20.0mm in shell length were $56.3\%$ and $60.0\%$, respectively, and $100\%$ for the clams >25. mm. The sex ratio of individuals >15.1 mm in shell length was about 1:1 $(\chi^2= 0.02,\;p>0.05)$. Number of the eggs released from each clam by the induction increased as the size of clam in terms of shell length increased. Mean number of the eggs from the second induction of the spawning was $75.35-84.30\%$ $(average\;79.81\%)$ of the number of the eggs released in the first spawning. Our data indicated that R. philippinarum in Komso Bay has one major spawning peak with over two minor spawning, and the interval of each spawning was estimated to be approximately 15-17 (average 16.5) days.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2001.11a
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• pp.69-70
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• 2001

Lectins have great potential as to determine the alternation of the distribution of cell surface carbohydrates during cellular development and differentiation. Here, we investigated the presence and distribution of cell surface carbohydrates on chicken primordial germ cells (PGCs) during the migration and gonadal stages using a variety of lectins. A total of six FITC-labelled lectins from several specificity classes were used: ConA (glucose/mannose), WGA (N-acetylglucosamine), STA (N-acetylglucosamine), DBA (N-acetylgalactosamine/galactose), UEA-I (fucose) and PHA-E (oilgosaccharide). As a results, PGC-specific binding was observed in STA. PGCs of migration stage (2.5- and 5.5-day embyos) were STA-positive whereas PGCs of 10-day embryonic gonad were not. The results suggest that N-acetylglucosamine residuse are present specifically in migrating chicken PGCs and changes during development.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.207-212
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• 2005

Directional (sinistral) asymmetry (DA) occurs when the traits of one side of a supposedly bilaterally symmetrical organism differ in a random way from those of the other side. We examined asymmetries in gonadal growth traits within both sexes of hatchery reared ayu, Plecoglossus altivelis. The pattern of the gonadal growth from hatching to 320 days after hatching was a type of DA except for the growth in gonad weight from 140 to 180 days after hatching, although the ovary of the right side tended to exhibit more pronounced DA phenomenon.