• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.4
• /
• pp.349-356
• /
• 2006

Gonad development in the sandfish Arctoscopus japonicus was investigated using a histological method. Specimens were collected monthly from April 2003 to March 2004, in the East Sea of Korea. The gonadosomatic index (GSI) of females began to increase in August, reached a maximum in November, and declined sharply in December. By contrast, in males, the GSI began to increase in June and reached a maximum in August. The annual reproductive cycle of A. japonicus can be divided into four successive stages in females: the early growing (January-March), late growing (April-August), ripe and spent (September-November), and recovery (December) stages. Males passed through early growing (January-April), late growing (May-July), ripe and spent (August-November), and recovery (November-December) stages. These results indicate that the spawning season was from October to December. The egg diameter of mature oocytes was 3.12$\pm$0.02 mm. The relationship between fecundity (F$_e$) and body length (BL) was F$_e$=0.4693BL$^{2.6825}$. Fecundity ranged from 483-2,254 eggs in a body length of 14.3-22.9 cm and increased with body length. The body length at 50% maturity was 14.80 cm, which corresponded to an age of 2.40 years.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.6
• /
• pp.835-842
• /
• 2013

Flathead flounder Hippoglossoides dubius is a commercially important fish in the coastal waters of Gangwon Province, which is its spawning ground and breeding habitat. A total of 1,669 gonads were sampled monthly from February 2011 to May 2013 to investigate ecological characteristics, such as variations in maturation and spawning by gonad index, visual maturity stage, histological observations and oocyte diameter. Males were numerically dominant over females in the fishing grounds year round. The spawning season was from January to April, and the peak was from February to March. Oocyte number as a measure of fecundity was between 27,372 and 915,209 eggs with a length range of 26.0-48.7 cm TL, while the largest oocyte grew to 0.9-1.4mm in egg diameter during its spawning season. The relationship between fecundity and total length was $F=0.0016TL^{5.2539}$. The smallest mature lengths of the females and males were 28.4 and 22.6 cm respectively, and the 50% mature lengths of females and males were 32.9, 26.9 cm respectively.

• Korean Journal of Ichthyology
• /
• v.7 no.1
• /
• pp.33-42
• /
• 1995

The reproductive cycle of the bitterling, Rhodeus uyekii was studied to observe the annual variations of gonadosomatic index(GSI), size frequency distribution of egg, ovipositor length and histological changes of gonad. GSI began to increase from February when the water temperature started to increase, and reached the maximum value in May, whereas it began to decrease from July and reached the minimum value in August which in the highest water temperature season. It began to incerase again but showed low value from September to November. The GSI remained stable thereafter. Monthly changes in GSI, ovipositor length, frequency of egg diameter and gonadal histology showed that the annual reproductive cycle was classified into the following successive phases : primary growing phase from September to November, quiescent phase in December, secondary growing and mature phase from January to February, ripe and spawning phase from March to June, and recovery and resting phase from July to August.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.3
• /
• pp.246-252
• /
• 2012

The age and growth of the blackthroat seaperch Doederleinia berycoides was investigated based on samples captured in the southern seas of Korea from January to December, 2006. Age was estimated by analyzing otolith growth rings. The spawning period was extrapolated from August to November based on monthly changes in the gonad somatic index. The relationship between total length and otolith radius was analyzed separately for each sex with TL=-15.6174+10.3274R for females and TL=-4.4083+7.0749R for males. From the parameters calculated using average total length and weight when the year ring was formed, the growth of D. berycoides was expressed by von Bertalanffy growth equations as $L_t=34.71(1-e^{-0.2557(t+0.2078)})$, $W_t=713.85(1-e^{-0.2557(t+0.2078)})^{3.1972}$ for females, $L_t=27.37(1-e^{-0.3388(t+0.7362)})$, $W_t=353.91(1-e^{-0.3388(t+0.7362)})^{3.1647}$ for males, and $L_t=34.20(1-e^{-0.2530(t+0.2871)})$, $W_t=674.10(1-e^{-0.2530(t+0.2871)})^{3.1171}$ for pooled sexes, where L is total length at age t.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.3
• /
• pp.184-191
• /
• 2000

Gametogenesis and the reproductive cycle of the marsh clam, Corbicula leana(Prime} were investigated monthly Hyongsan estuary, Korea from January to December 1998 by histological observation. C. leana had separate sexes, and oviparous. The gonads were located between the sub-region of mid-intestinal gland in visceral cavity and reticular cennective tissue. The ovary and testis were composed of a number of ovarian and testicular tubules, respectively, Mature oocytes were characterized by germinal vesicles with nucleoli and their sizes ranged $70\;to\;80{\mu}m$ in diameter. A number of mesenchymal tissues and pigment granular cells were distributed in the growing oocytes and spermatocytes during early developmental stages. With the further development of gonad, these tissuse and cells gradually disappeared. The monthly changes in the fatness index were closely related to reproductive cycle. Minimun size for sexual maturity was reached over 10.0 mm in shell length. The reproductive cycle could be classified into 6 stages : multiplicative (March to April): early growing and growing (May to June), mature (July to August), spent (September), degenerative (October) and recovery (November to February).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.3
• /
• pp.219-224
• /
• 2000

Reproductive biology of the naked-headed goby, Faronigobius gymnauchen was investigated by means of histological methods. The ovary was consisted of several ovarian lamellae and the oogonia originated from the inner surface of the ovarian lamella. The testis was seminiferous tubule One in internal structure. Seminiferous tubule was consisted of many testicular cysts which contained numerous germ cells in a same developmental stage. The size of group maturity was 4.5 cm intotal length. Gonadosomatic index(GSI) of the female and male was the highest in June and July, respectively. Reproductive cycle could be classified into the growing ($January{\~}March$), maturation ($April{\~}May$), ripe and spent (June{\~}July$), and recovery and resting ($August{\~}December$). Oocyte development was group-synchronous, and yolk nucleus was observed in the early growing oocyte.

• Development and Reproduction
• /
• v.20 no.4
• /
• pp.305-314
• /
• 2016

The marine medaka, Oryzias dancena is a suitable sample as a laboratory animal because it has a small size and clearly distinguishes between female and male. Data on the growth and maturity of the diploid and triploid sea cucurbit species suitable for laboratory animals are very useful for studying other species. Triploidy was induced in the marine medaka by cold shock treatment ($0^{\circ}C$) of fertilized eggs for 45 min, applied two minutes after fertilization. The diploid and triploid male fish were larger than their female counterparts (P<0.05), and the concentrations of thyroid stimulating hormone (TSH) and thyroxine (T4) were higher in the induced triploids over 1 year (P<0.05). In both the diploid and tri-ploid groups the concentrations of TSH and T4 were higher in the male fish than in the females (P<0.05), while the testo-sterone and estradiol-$17{\beta}$ concentrations in the induced triploids were lower than in the diploids (P<0.05). The gonadosomatic index (GSI) of the triploid fish was lower than that for the diploids, and the GSI for females in each ploidy group were higher than that for the males. For both groups the GSI was highest at 4 months of age, and decreased thereafter to 12 months. Analysis of the gonads of one-year-old triploid fish suggested that the induction of triploidy probably causes sterility in this species; this effect was more apparent in females than in males.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2002.11a
• /
• pp.33-37
• /
• 2002

The present was performed to identify the effects of tributyltin (TBT) in the immature mice testes. 3-week-old male ICR mice were orally administrated on one time basis of TBT dose of O (Vehicle control, VC), 25 (TBT 25 mg/kg, T$_{25}$ ), 50 (TBT 50 mg/kg, T$_{50}$ ), 100 (TBT 100 mg/kg, T$_{100}$ ) mg/kg per each one. After 3 days the time treated of TBT, mice were sacrified and wighted body, testis, epididymis, seminal vesicle, vas deferens, and prostate. As the result of weighing, wights of each oragan and gonad index were tendency decresed in comparing groups of TBT treated with that (C) of unteated (p <0.05). As the result of examination of steroid hormones in the immature male mice, The concentrations of serum and intratesticular testosterone were significatly increased rather than the control group. But concentrations of estradiol were decresed objectly. A group of the highest change of concentrations of steroid hormones is T$_{100}$ . The high dose group, T$_{100}$ , was decreased all of concentrations of steroid hormones rather than those of T$^{25}$ . The result of observation with histological changes in testis showed a tendency for innercellular wall to increase damage and extinction in seminiferous tubles. As the result of investigation apoptotic cell numbers in the testis using teminal deoxy-nucleotidyl transferase -mediated dUTP-digoxygenin nick end-labeling immunohistochemical straia, The ratio of Apoptic cells significantly was incensed in depending on treatment of TBT does. In conclusion, these results shows that TBT triggers apoptosis on reproductive cell in testis and changes level of concentrations of steroid hormones in the immature male mice , as endocrine disruptors (EDs).

• Fisheries and Aquatic Sciences
• /
• v.17 no.1
• /
• pp.115-121
• /
• 2014

Eyestalk ablation (ESA) is commonly used in aquaculture to stimulate ovarian maturation in crustaceans, and methyl farnesoate (MF) affects crustacean molting and reproduction. To investigate the physiological effects of ESA and MF treatments on the shrimp Litopenaeus vannamei, we compared the effects of single eyestalk removal and MF injections. The ESA group had the lowest survival rate (50%), and individuals in the $0.1{\mu}g$ and $1.0{\mu}g$ MF-treated groups had survival rates of 80 and 73.3%, respectively. Conversely, molting numbers were highest in the ESA group, and similar to those of the 1.0-${\mu}g$ MF group. To investigate shrimp growth, we measured body weight during the experimental period and found that individuals in the ESA and $1.0{\mu}g$ MF groups showed significant increases in body weight. Furthermore, to investigate the effects of ESA and MF treatments on gonadal maturation, the gonad somatic index (GSI) was calculated after the experiment. All treated groups (ESA and MF) had higher GSI values than the control group, but the ESA and $1.0{\mu}g$ MF groups were not significantly different. Using histological ovary analysis, we determined that all treated groups showed indications of the previtellogenic stage, unlike the control group (immature stage). These results suggest that the high-MF-concentration treatment produced effects similar to those of ESA with respect to molting number, growth, and ovarian maturation.

• Clinical and Experimental Reproductive Medicine
• /
• v.21 no.3
• /
• pp.305-314
• /
• 1994

19-norandrostenedione(19-NORA) is known as an intermediate in the metabolic pathway from androstenedione to estrone. Administration of esterified 19-nortestosterone, anabolic steroid, reduces serum gonadotropin and testosterone concentration, and results in reversible azoospermia in men. 19-NORA have been isolated from testis, but its function in testis is not clear yet. Therefore, this study was designed to determine the effect of 19-NORA on steroidogenesis and on spermatogenesis. 19-NORA was administrated by single intratesticular injection to adult male rats weighing 350-400 g in dose of 1 mg/50${\mu}l$. The serum and testis were collected on 1, 3, 7, 12, 48 hr after injection. The histological differences in testis were observed by routine paraffin method. The concentrations of testosterone and estradiol in serum and in left testis were determined by the conventional radioimmunoassays. One hour after 19-NORA treatment, serum concentrations of testosterone and estradiol increased significantly, compared to those of pre-treated(0 hr) group, and reduced gradually to the control level on 7 hour after injection. The concentration of testosterone in left testis increased slightly 1 hour after injection, and estradiol level increased significantly(p<0.05). Also, testosterone and estradiol level of control group revealed no difference with pre-treated (0 hr) group. Gonad index, structure of seminiferous tubules, and the number of step 7 th spermatid were simillar to control group. The present study suggests that the elevation of testosterone level results from increment of estradiol followed by the rapid metabolism of 19-NORA at 7 hour after injection, and then testosterone concentration may be recovered to control level by feedback mechanism of hypothalamus-hypothysis-testis axis.