• Journal of Aquaculture
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• v.17 no.1
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• pp.81-88
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• 2004

Annual gametogenic cycle of Manila clam Ruditapes philippinarum collected from Shi-Heung-Ri beach in Jeju was investigated for the 12 month period from May 2001 to April 2002. Water temperature varied from 10 to 27$^{\circ}C$ and salinity from 27 to 35 psu during the course of study. Most of the clams collected in March were in indifferent or in early developing indicating that clams initiated gametogenesis when water temperature becomes 14 to 15$^{\circ}C$. In early June, most of the clams were in developing, expanding follicles and exhibiting growing oocytes. Fully ripe gonads were observed in clams collected during late June to early August. Spawning clams were observed as early as in early June although the spawning activity reached its maximum in early August. Condition index (CI) was rapidly increased from July to early August and then dropped in late August, indicating that most of clams in Shi-Heung-Ri beach spawn in late summer when water temperature was within a range of 25 to 27$^{\circ}C$.

• Advances in Traditional Medicine
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• v.10 no.2
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• pp.103-110
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• 2010

The seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug ($Nordette^{(R)}28$) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and $17{\beta}$-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and $17{\beta}$-estradiol probably by affecting hypothalamic-pituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.379-388
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• 2011

The mechanism by which gonadotropin-releasing hormone (GnRH) and dopamine (DA) control gonadotropin (GTH) release was studied in male and female rainbow trout using cultured pituitary cells obtained at different reproductive stages. The mechanisms of follicle-stimulating hormone (FSH) release by GnRH and DA could not be determined yet. However, basal and salmon-type GnRH (sGnRH)- or chicken-II-type GnRH (cGnRH-II)- induced luteinizing hormone (LH) release increased with gonadal maturation in both sexes. LH release activity was higher after sGnRH stimulation than cGnRH-II stimulation at maturing stages in both sexes. The GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) suppressed LH release by sGnRH stimulation in a dose-dependent manner, although the effect was weak in maturing fish. The role of DA as a GTH-release inhibitory factor differs during the reproductive cycle: the inhibition of sGnRH-stimulated LH release by DA was stronger in immature fish than in maturing, ovulating, or spermiated fish. DA did not completely inhibit sGnRH-stimulated LH release, and DA alone did not alter basal LH release. Relatively high doses ($10^{-6}$ or $10^{-5}M$) of domperidone (DOM, a DA D2 antagonist) increased LH release, which did not change with reproductive stage in either sex. The potency of DOM to enhance sGnRH-stimulated LH release was higher in maturing and ovulated fish than in immature fish. These data suggest that LH release from the pituitary gland is controlled by dual neuroendocrine mechanisms by GnRH and DA in rainbow trout, as has been reported in other teleosts. The mechanism of control of FSH release, however, remains unknown.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.41-51
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• 2003

Reproductive cycle with the gonadal development of Ruditapes philippinarum can be classified into five successive stages by histological observations: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (May to October), and spent/inactive stage (August to February). Changes in total protein contents in the adductor muscle tissues reached the maximum in the early and late active stages (February) and appeared the minimum in the ripe and partially spawned stages (May), while changes in their contents in the visceral mass tissues reached the maximum in the ripe and partially spawned stages (June) and gradually decreased in the partially spawned stage (June to October). On the whole, changes in total protein contents showed a negative correlationship between the adductor muscle and visceral mass tissues (r = -0.292, p < 0.05). Changes in total lipid contents in the adductor muscle tissues reached the maximum in the inactive and early active stages (January) and sharply decreased in the early and late active stages (February), while their contents in the visceral mass tissues reached the maximum in the ripe and partially spawned stages (April) and gradually decreased in the partially spawned stage (to October). On the whole, changes in total lipid contents showed a negative correlationship between the adductor muscle and visceral mass tissues (r = -0.699, p<0.05). Changes in glycogen contents in the adductor muscle tissues reached the maximum in the late active and ripe stages (April) and rapidly decreased in the partially spawned stage (May to October), while their contents in the visceral mass tissues reached the maximum in the early and late active stages (February) and rapidly decreased in the late active stage (March). Thereafter, their levels gradually increased in the ripe and partially spawned stages (April to July). On the whole, changes in glycogen contents appeared no correlationship between the adductor muscle and visceral mass tissues (r = 0.062, p > 0.05). These results indicate that the adductor muscle and visceral mass tissues are an important energy storage and nutrient supply organ in the Manila clams, and the nutrient contents of the adductor muscle and visceral muscle tissues change in response to gonadal energy needs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.266-280
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• 1989

Gonadal maturation of the Korean pomfrets, Pampus echinogaster (Basilewsky) and Pampus argenteus (Euphrasen) were histologically investigated based on the samples captured in the East China Sea from January 1987 to December 1988. Gonadosomatic index (GSI) of P. echinogaster began to increase from March, and reached maximum between May and July. It began to decrease from July and reached mini-mum between August and February. P. argenteus had a similar cycle, however, P. argenteus has higher values in April than P. echinogaster. Hepatosomatic index (HSI) were positively related to GSI. HIS of P. echinogaster and P. argenteus reached maximum in $April\~July$ and $April\~August$, respectively, Fatness coefficient of two Pampus species were low in the summer, and high in the winter. Ovary is of saccular structure, and testis is of lobular structure. From February, the early oocyte (ca. $100\mu$ in diameter grows) rapidly at the germinal epithelium of ovarian sacs. From March to April the oocytes grew up to cu $400\~500\mu$ in diameter. At this stage, the yolk globules are accumulated rapidly in the cytoplasmic layer. From May, the oocytes roached ca. $650\~850\mu$ in diameter, and they are spawned in $May\~July$. After spawning the residual follicles and remained ripe eggs degenerate. From February, spermatogonia grows into spermatocyte on the epithelium of the testicular lobuli. From May, spermatozoa appeared and spawning occurs. After spawning, the epithelium is thickened and the remained spermatozoa degenerate. Annual reproductive cycle of two Pampus species could be divided into four successive stages: Growing stage ($March\~April$), Mature stage ($April\~May$), Ripe and spent stage ($June\~July$) and Recovery and resting stage ($August\~January$). Absolute fecundity of P. echinogaster was $9,441\~135,294$, and that of P. argenteus was $50,678\~221,894$. Absolute fecundity of two Pampus species were positively related to body length and total weight. Relative fecundity was positively related to body length, while it was reversely related to total weight. The increasing rate of absolute fecundity of P. echinogaster was lower than P. argenteus. In P. echinogaster half of female and male reached first maturity at body length of $15.0\~$17.9cm and $12.0\~14.9cm$, respectively. All of females and males reached first maturity at body length of $18.0\~20.9cm$ and $21.0\~23.9cm, respectively. In P. argenteus all of females and males reached first maturity at body length of 18.6cm and 16.7cm$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.135-144
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• 1980

The reproductive cycle and the breeding season of the freshwater clam, Anodonta (Sinanodonta) woodiana (Lea) have been investigated by histological examination of the gonadal development under photomicroscopy. The materials were monthly collected from the Nakdong River for one year from September 1979 to August 1980. Sexuality of Anodonta (Sinanodonta) woodiana is dioecious, and the species are ovoviviparous. The gonads are irregularly arranged from the subregion of mid-intestinal gland in visceral cavity to reticular connective tissue of foot. The ovary is composed of a number of small ovarian sacs, The epithelium of ovarian sac has a function of the germinal epithelium. Oogonia actively proliferate along the germinal epithelium of the ovarian sac, in which young oocytes are growing. The testis is composed of a number of seminiferous tubules, and the epithelium of the tubule has function of germinal epithelium, along which spermatogonia actively proliferate. A great number of undifferentiated mesenchymal tissue and eosinophilic granular cells are abundantly distributed between the growing oocytes and spermatocytes in the early development stages. With the further development of the ovary and testis these tissues and cells gradually disappear. Then the undifferentiated mesenchymal tissue and granular cells are considered to be related to the growing of the oocytes and spermatocytes. The gonads had function year-round the individuals which have various developmental stages of gonads appearing all the time. Spawning continued year-round except for the period of high temperature of water, during August and September. The peak spawning seasons appeared twice a year between January and March, and between June and July in 1980. Individuals which have trochophore larvae in the marsupium of the adult appeared year-round except September 1579 and August 1980. The rate of individuals which have glochidia in the marsupium was 72.7 percent in May 1980 which was the highest brooding fate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.523-528
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• 1984

The small filefish, Rudarius ercodes, generally spawning from mid May to early October in the natural habitat, was exposed to various photoperiod and temperature regimes. These environmental effects on the gonad activity, regression and recrudescence were experimentally investigated based on the mechanism of reproductive cycle. Spawning season was initiated in the early spring with the gonad activated by long photoperiod(13L) and stimulated by compensatory temperature rising. Even when the gonad activated readily at the above critical daylength (12L to 13L)was kept back at the below if, it went on maturing. At the end of spawning period (mid September), since the shortening of daylength (12L) resulted in the gonad regression regardless of temperature, the short daylength might be related to the termination of spawning in situ. When the regressive gonad at the post spawning period was treated by the above 13L: $20^{\circ}C$ condition, it could recrudesce and bring forth even spawning. From this fact, the feasible control of annual reproductive cycle of small filefish was recognized. But even in the long daylength, the temperature above $28^{\circ}C$ was preventive of gonad maturation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.413-431
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• 1992

Gonadal development, fertilization and egg development in the maternal body and reproductive cycle of ovoviviparous rockfish, Sebastes inermis, were investigated histologically. Gonadosomatic index(GSI) of male and female were increased from September and reached maximum values in December. In the male, GSI decreased from January, but in the female maintained high values till February and decreased from March. Hepatosomatic index(HSI) was related to GSI conversely. In both sex, HSI increased from February and reached maximum in August as the gonad were degenerating and resting, and began to decrease from September as gonad were glowing. This ovoviviparous rockfish copulates in December. Fertilization with sperms maintained between ovulated oocytes in the ovary occurs in January mainly. Egg development in the ovarian cavity and discharging of hatched preiarva occurs from January to February. The reproductive cycle includes the successive stages: Growing(September), Mature (October-November), Ripe and Fertilization(Decembr-Janua), Egg development and Discharging of hatched larva(January-February), Degeneration and Resting(February-August). According to the frequency distribution of egg diameter and histological observation, the ovoviviparous rockfish discharged the prelarva at a time in a spawning season. The sexual maturation is first attained at 2 ages. All females and males reaches first maturity at body length of 17.1cm and 15.1cm respectively. The mean number of the embryos increased with the increase of the total length of female.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.184-192
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• 2006

To investigate reproductive cycle of Tridentiger obscurus in Jeju, total 408 fish were collected in brackish area (May 2004 to August 2005) and total 271 fish were collected in tidal pool (July 2004 to August 2005), respectively. Water temperature ranged $11.0{\sim}21.6^{\circ}C$ in brackish area. Water temperature of tidal pool ($11.1{\sim}24.5^{\circ}C$) in 2005 was similar to that of brackish area although it were highest $30.1{\sim}29.2^{\circ}C$ from July to August in 2004. In brackish area, female gonadosomatic index (GSI) increased in April and maintained high values from May to August. The reproductive cycle can be grouped into the following successive stages in the ovary: immature (November to May), maturing (March to September), ripe and spawning (May to September), and degenerating (July to December). In the tidal pool, female GSI rapidly increased in April and maintained high values until July in 2005. However, it has been low in July 2004 when water temperature was highest. The reproductive cycle can be grouped into the following successive stages in the ovary: immature (August to April), maturing (March to August), ripe and spawning (March to July), and degenerating (July to August 2004 and August 2005). Fecundity of mature female ranged from 1,214 to 12,109 in brackish and ranged from 2,427 to 13,892 in tidal pool area. The fecundity of fish in the tidal pool was significantly higher than that of fish in brackish area. Fecundity was correlated positively with total length and body weigh. Although the large group (> 111 mm total length) in brackish area observed only in spawning season, one in the tidal pool observed from October 2004 until next spawning season. Frequency of the large group was 0 to 12% and 11.4 to 57.9% in brackish area and tidal pool, respectively. These results were indicated that gonadal development of T. obscurus was affected to water temperature and day length.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.629-636
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• 1999

Gonadal development, gametogenesis, reproductive cycle, egg-diameter and composition, condition factor, and the first sexual maturity of the clam, Potamocorbula amurensis were investigated by histological observation. Samples were collected monthly from the tidal flat of Moonpo, Puan-gun, Chollabuk-do, west coast of Korea from November 1996 to October 1997. P. amurensis is dioecious and oviparous. The gonads were composed of a number of gametogenic follicles. The oogonia and fully ripe oocytes were $9\~12\mu$m and $50\~60\mu$m in diameter, respectively. Each of the spermatogenic follicle formed stratified layers composed of spermatogonia, spermatocytes spermatids, and spermatozoa in groups on the follicular wall. The reproductive cycle of P. amurensis could be classified into five successive stages: early active, late active, ripe, partially spawned, and recovery. Spawning occurred twice a year from May to July and from September to October, the main spawning seasons also appeared twice a year between May and June, and in October when the water temperatures reached above $18^{\circ}C$. The monthly changes in the condition factor were closely related with the reproductive cycle. Minimum size for the sexual maturation of female and male were 8.1 mm in shell length. There were two patterns for the gametogenesis: 1. After spawning, the undischarged ripe oocytes and spermatozoa in the follicles were degenerated and absorbed, but in part, the existing follicles were not contracted significantly and then they took part in new gametogenesis within one or two months (especially, in summer). 2. After spawning, each follicle was contracted, thereafter gametogenesis again occurred in newly formed follicles.