• Applied Microscopy
• /
• v.28 no.4
• /
• pp.447-463
• /
• 1998

This study was carried out to investigate the histomorphological changes and the electrophoretic patterns of egg components, obtained from 100 of 2-year-old female catfishes (Silurus asotus). Female Korean catfishes collected in the vicinity of Chollabukdo have synchronous ovaries which discontinously ovulate eggs during the breeding season (from late May until early July). The fishes were killed by severing the spinal cord just posterior to the head after immobilization with tricaine methanesulfonate (MS 222). Especially, the light microscopic and ultrastructural changes of ooplasm and follicular membranes of oocytes, were examined by means of light and transmission electron microscopy. The size of the nucleoli and number of the yolk granules increased as the oocyte groved. Yolk granules were deposited in the oocyte as fluid Due to tile presence of large early and late maturing oocytes, their ovaries were enlarged, transparent, granular and greenish in color. As the percentages of fish in late maturing oocyte (LMO) and ripe oocyte (RO) stage increased from March to April, mean gonadosomatic index (GSI) values (19.95%) increased. Zona radiata changed from squamous into cuboid in shape in the early maturing oocyte (EMO) stage. Processes, microvilli, from the zona radiata and from the oocyte grow, and make contact with each other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radials becomes more compact and devoid of pore canals during oocyte maturation. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in both gonadosomatic index and macroscopic appearance. The main cytological changes such as increase in size of cell, nucleus, nucleolus, and increase in number of nucleoli and mitochondria demonstrated with electron microscopy in the previtellogenic oocytes of Korean catfish, provided evidences for important synthetic processes in an early preparatory phase of oocyte development. The electrophoretic pattern of major band in mature stage was much thicker (24 k, 66 k, 90-110k dalton) than that in previtellogenic phase.

• Korean Journal of Ichthyology
• /
• v.31 no.3
• /
• pp.141-149
• /
• 2019

This study presents data on spawning season, weight-length relationships (WLRs) and condition factor of Gadus chalcogrammus inhabiting the middle East Sea, Korea. Monthly changes in the gonadosomatic index (GSI) revealed that the spawning period was from December to March. Overall value of the exponent b, estimated by nonlinear least squares from weight and length data was 2.806, ranging from 2.778 for female fishes to 2.985 for immature group. The b values were similar between spawning and non-spawning, and between female and male fishes, but it was significantly higher for immature than mature fishes. The condition factors were significantly higher for immature than mature groups, and during non-spawning than spawning periods, but it was not significant between male and female fishes.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.6
• /
• pp.1000-1006
• /
• 2021

The maturity and spawning of the common octopus Octopus vulgaris were studied using 317 samples collected monthly from January to December of 2020 from the coastal waters of Yeosu, Korea. The mantle length (ML) of O. vulgaris ranged from 5.1 to 19.7 cm and body weight (BW) ranged from 117.6 to 3,645.4 g. We analyzed monthly changes in sex ratio, gonadosomatic index (GSI), histological maturity stage, and body weight at 50%, 75% and 97.5% group maturity. The sex ratio was 1:1.02, which was not significantly different from the value that expected. Based on histological observation of the gonad development and gonadosomatic index, the spawning periods lasted throughout the year, with peak spawning periods estimated from March to April and July to August. The percentages of sexually mature females estimated using a logistic equation were over 50% at 554.46 g BW, 75% at 1,134.38 g BW and 97.5% at 2,474.22 g BW respectively.

• Fisheries and Aquatic Sciences
• /
• v.27 no.2
• /
• pp.100-110
• /
• 2024

Biometric evaluation and reproductive biology of Oreochromis niloticus were studied from Geray Reservoir. Between November 2021 and August 2022, 316 O. niloticus specimens were collected from this reservoir. The observed male to female sex ratio was 1:1.14, which was statistically insignificant compared with the hypothetical 1:1 sex ratio (X² = 1.27, p > 0.05). The length-weight relationship was curvilinear with allometric growth (b < 3) and statistically significant from the expected isometric growth pattern (b = 3). The regression equation for females was TW = 0.0264TL^2.72 (r² = 0.90, n = 168), males (TW = 0.0183TL^2.79, r² = 0.93, n = 148), and combined sexes (TW = 0.0229TL^2.76, r² = 0.91, n = 316). Gonadosomatic index (GSI) ranged from 0.8 to 1.4 (males) and 1.8 to 4.9 (females). The breeding season lasted from March to June, with a GSI peak in April. Fecundity ranged from 279 to 1,528 eggs./fish, with a mean of 1,025 eggs./fish. The correlation between absolute fecundity and length was more significant (F = 0.76TL^2.8, R² = 0.94, p < 0.05) than with weight (F = 17.683TW^0.71, R² = 0.92, p < 0.05). This study provides basic information on the biology of O. niloticus in the Geray Reservoir for future fishery management tools for the conservation and utilization of this valuable freshwater fish.

• Applied Microscopy
• /
• v.31 no.1
• /
• pp.19-35
• /
• 2001

Outlines for plasma $estradiol-17\beta$, components, electrophoretic patterns, and ultrastructural changes were obtained in female rainbow trout (Oncorhynchus mykiss) during the seasonal reproductive cycles. Plasma $estradiol-17\beta$ under the natural conditions, exhibited distinct seasonal variation, peaking very late in vitellogenic season during September, decreasing gradually the halt of spawning in December, and ultimately falling during the early stages of seasonal ovarian recrudescence in February and March. This change in $estradiol-17\beta$ appeared to stimulate vitellogenin production as evidenced by increases in plasma calcium, phosphorus, glucose, albumin and total protein levels. The electrophoretic patterns of late maturing or spawning oocytes were stained more intensively than those of late perinucleolus oocytes (molecular weights of approximately 70,000 and 200,000). Two protein bands were found in the SDS-PAGE separation, coincident with the $estradiol-17\beta$ hormone peak. Gonadosomatic indices (GSI) significantly increased from October to January, and showed the highest peak in January, coinciding with the numerically abrupt increase of ripe ova in female. A positive correlation (r=0.701, p<0.01) was established between plasma $estradiol-17\beta$ levels and the gonadosomatic index during the prespawning. The highest level of hepatosomatic index (HSI) observed in December. During the breeding season (December), the gonadotropes were large and filled with GTH-containing inclusions such as granules and globules. The vitellogenic phase began as late perinurleolus oocytes became transformed into early maturing oocytes through the accumulation of yolk, and oocytes reached the late maturing stages as the ooplasm was completely packed with yolk. Marked ultrastructural changed in the granulosa cells during nuclear migration involve the dilation of the rough endoplasmic reticulum and the appearance of the rod-shaped mitochondria with tubular cristae. Microvilli (finger-like projections), from the zona radiata and from the oocyte grew, and made contact with each other in the pore canals of the zona radials during vitellogenesis, but were withdrawn as the zona radiata became more compact and devoid of pore canals during oocyte maturation. The zona radiata grew to a tripartite structure such as an outer thin homogeneous layer, and two inner thick helicoidal layers (zona radials interna and zona radiata externa). Under the normal conditions, the ovarian follicle influenced the histological development and periodical secretion of the hormones , sufficient for a oogenesis and gonadal steroid production.

• Korean Journal of Environmental Biology
• /
• v.22 no.1
• /
• pp.159-166
• /
• 2004

The effects of polychlorinated biphenyls (PCBs) on the reproduction of the oily bitterling, Acheilognathus koreensis were investigated using histological methods. The experimental fishes were exposed to 0. 3.4, 9.3 and 25.8 ${\mu}g\; L^{-1}$ PCBs fey 8 weeks. Dead fishes and abnormal behavior were not observed in control and PCBs exposure group. In compared with control group, PCBs exposure fishes showed differences of gonadal development, gonadosomatic index (GSI), hepatosomatic index (BSI), nuptial color index (NCI) and ovipositor length index (OLI). These results showed that PCBs could disrupt reproductive process in the fish.

• Korean Journal of Ichthyology
• /
• v.23 no.4
• /
• pp.261-268
• /
• 2011

To clarify the annual reproductive cycle of the Korean perch, Coreoperca herzi, the seasonal changes in gonadosomatic index (GSI), hepatosomatic index (HSI), histological aspects of gonad and liver, and plasma levels of sex steroid hormones were investigated from June 1994 to April 1996. The annual variations of GSI and HSI were positively related to the plasma levels of sex steroid hormones. Estradiol-$17{\beta}$ (E2) and testosterone levels were raised during the April to May. Based on the related results, annual reproductive cycle of the fish could be divided into five successive stages; 1) Growing stage (from February to March: GSI was increased rapidly and oocytes with yolk vesicle was increased. Nucleus migrates toward the animal pole. Spermatids were activated from the epithelial tissue of lobuli). 2) Maturation and spawning stage (from April to June: Oocytes were accumulated yolk globules. Active spermatogenesis was observed). 3) Degeneration or stagnation phase (from July to August). 4) Recovery phase (from September to November) and 5) resting phase (from December to January). The main spawning period was in May.

• Korean Journal of Ichthyology
• /
• v.6 no.2
• /
• pp.222-236
• /
• 1994

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.

• Animal cells and systems
• /
• v.13 no.1
• /
• pp.83-89
• /
• 2009

Investigations were made on population biology of Pampus echinogaster (Basilewsky, 1855) in the coastal areas of Korea, Yellow Sea, between August 2005 and July 2006. Population structure was not significantly different between male and females. Monthly variation of gonadosomatic index (GSI) of both sexes defined spawning period extending from March through July. A similar pattern was also observed in change at maturity stages. For males and females GSI was positively correlated with hepatosomatic index (HSI). Fecundity, ranging from 41,250 to 103,610 eggs, was related to body size, indicating that body size is the useful determinant of fecundity. The sexual maturity ($L_{50}$) was estimated as 14.98 cm TL for males and 19.32 cm TL for females. Parameters of growth estimated by the modified von Bertalanffy growth function model showed that the values of $L_{\infty}$ and K for combined data were 39.12 cm TL and 0.65 $yr^{-1}$. The growth performance index of this study (2.75) was higher than that of the previous study (2.45). This difference could be attributed to sampling method. The recruitment patterns indicated one normally distributed group. Percentage of the recruitment was 51.04% in the spawning season and the highest in August (19.78%).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.5
• /
• pp.398-403
• /
• 2006

Gonad development and the gametogenic cycle of pen shells, Atrina pectinata, collected from November 2004 to October 2005 in the coastal waters of Jangheung, Jeollanam-do, Korea were investigated histologically. The clams are dioecious. The gonads consist of a number of gametogenic follicles. The sex ratio (Female:male) was 1:1.2. The gonad index (GI) reached a maximum in May and a minimum in July. The condition index (CI) reached a maximum in April and a minimum in June. The gonadosomatic index (GSI), GI and CI all increased with gonad development. The gametogenic cycle of the clam could be divided into five stages: the degenerative/inactive (August to October), early active (November to March), late active (December to April), ripe (May to June) and spent (June to July) stage.