• The Korean Journal of Zoology
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• v.30 no.4
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• pp.432-444
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• 1987

Very early stage of chick embryo cultivated in the medium containing DLtryptophan by beaker method has been investigated in vitro morphologically using electron microscopy at cellular level and found that the development of tryptophan treated chick embryos corresponding to 18∼66 hrs incubation was impaired and york granule degradation was significantly delayed. It was also found that DNA, RNA and protein biosynthesis of tryptophan treated chick embryo was greatly lowered than those of control group. Conversion of L-tryptophan into serotonin was traced using 14C-L-tryptophan and found that 13.8cA of added radioactivity was recovered from serotonin formed during 18 hrs incubation and the amounts of serotonin formed were depend upon added amount of tryptophan in e99 yolk. It seemed that the serotonin formed from external tryptophan might inhibit the degradation of yolk granule by feedback mechanism, resulting in malformation of chick embryogenesis.

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.252-257
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• 2017

The oogenesis of the Microphysogobio yaluensis was investigated using light microscopy. Various developmental oocytes appeared in the ovary of the M. yaluensis. The oogenesis is largely divided into four stages: nuclear-chromatin stage, peri-nucleoli stage, vitellogenesis (yolk vesicle and yolk granule stages), and mature stage. The nuclear-chromatin is distributed in a large germinal vesicle as threads. The peri-nucleoli stage has many acidic nucleoli lining at the inner side of the nuclear membrane and an egg envelope just weakly starts. As the oogenesis gradually proceeds, they change to the vitellogenesis stage. The oocyte become to drastically increase and the marginal area of the ooplasm is covered with many vacuoles showing no negative reactions with hematoxylin and eosin staining, called the yolk vesicle stage. Many yolk vesicles-owned oocyte largely increase and as the development continues, its ooplasm is changed from the yolk vesicles to the yolk granules of eosinophilic. At the mature stage, lots of granules merged into a big yolk mass, acidophilic. Even at the mature stage, the egg envelope was still thin between the ooplasm and the follicular layer of the oocyte.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.16-23
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• 2007

Oocyte surface in two Korean minnows, Rhynchocypris oxycephalus and R. kumgangensis was examined by light and electron microscope. In two species, the development of the oocyte was similar, but the follicular layer surrounding full-grown oocyte showed an evident difference. In R. oxycephalus, the follicular layer at the yolk vesicle stage became bilaminar with the retention of its outer squamous cell layer and the acquisition of an inner cuboidal or round cell layer just over the zona radiata. As the oocyte grows, the cuboidal cells of the inner follicular layer began to be replaced by columnar cells. At the yolk granule stage, the columnar cells secreted mucin to their cytoplasm (adhesive materials) and then surround the entire oocyte, as bundles of fence-shaped structures. Whereas, although the follicular layer of R. kumgangensis had an outer squamous layer and an inner cuboidal or round cell layer at the yolk vesicles as in R. oxycephalus, no inner cells were more changed with the retention of its cuboidal or round cells. Finally, in R. kumgangensis, the adhesive materials did not occur. In Korean two minnows, the structural difference in the oocyte surface seems to be related to their habitats and spawning characteristics as well as taxonomic characters.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2005.07a
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• pp.52-52
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• 2005

Oogenesis, the gonadosomatic index (GSI), reproductive cycle and first sexual maturation of the female Neptunea (Barbitonia) arthritica cumingii have been 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. In late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in the cytoplasm. In particular, compared with the results of other gastropods, it is 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 menbrane, Monthly changes in the gonadosomatic index in females were studied in 2002 and 2003 were closely associated with ovarian developmental phases. Spawning occurred between May and August in 2002 and 2003 and the main spawning occurred between June and July when the seawater temperature rose to approximately 18${\sim}$23${\circ}$C. The female reproductive cycle can be classified into five successive stages: early activestage (Septmber to October), late active stage ( November to February), ripe stage (February to June), partially spawned stage (May to Aygust), and recovery stage (June to August).

• Korean Journal of Animal Reproduction
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• v.15 no.3
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• pp.207-220
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• 1991

This study was carried out to investigate the ultrastructural changes of ooplasm and follicular membrane of oocytes, obtained from 150 of 3-year-old female rainbow trout(Oncorhynchus mykiss). All data were collected from March in 1989 to February in 1990, and from August to October in 1991. The size of the nucleoli and number of the yolk granules increased as the oocyte growed. Yolk granules were deposited in the oocyte as crystalline granules. Due to the presence of large early and late maturing oocytes, their ovaires were enlarged, transparent and granular. The lattice was broken down at hydration, leaving the egg transparent. As thepercentages of fish in LPO and EMO stage increased from September to October, Mean GSI values increased. Follicle cells such as granulosa cell and thecal cell change a squamous into cuboid shape in LPO and EMO stage. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in bothgonadosomatic index and macroscopic apearance. Under the natural conditions,t he ovarian follicle influences the histological development and periodical secretion of the hormones, sufficient for a oogenesis and gonadal steroid production. The electrophoretic pattern of major band in mature stage was much thicker(70∼110k dalton) than that in previtellogenic phase.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.247-260
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• 1992

This study was carried out to investigate the histomorphological changes of ovaries obtained from 100 of 1-year-old female Korean loach(misgurnus anguillicaudatus). The light microscopic and ultrastructural changes ofooplasm and follicular membranes of oocytes, were observed by lightand transmission electron microscope during the reproductive cycle. All data were collected from November in 1991 to May in 1992. The results obtained in this study were as follows: The size of the nucleoli and number of the yolk granules increased as the oocytes grown. Yolk granules were loosely deposited in the oocytes as crystalline granules. Due to the presence of large early and late maturing oocytes, their ovaries were enlarged, transparent, granular and yellowish in color. The lattice was broken down at hydration, leaving the egg transparent. As the percentages of fish in LMO and RO stage increased from March to April, mean gonadosomatic index(GSI) values(18.49%) increased. Zona radiata change a squamous into cuboid shape in EMO stage. Processes from the granulosa cells and from the oocyte, microvilli grow and make contact with other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radiata 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 GSI and macroscopic appearance.

• 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).

• The Korean Journal of Zoology
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• v.29 no.3
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• pp.215-233
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• 1986

The effect of tryptophan on brain formation at the early stage of chick embryo has been investigated morphologically using electron microscope. The electron micrographs of cerebral cortex cells of $5\\sim10$ day old chick embryo, which received 1.0mg of tryptophan showed that the irregularity, evagination and disruption of nuclear membrane and nuclear chromatin condensation, nucleolar chromatin margination and segragation. Hypertrophy of stalks, vesicles, and vacuoles can be seen and dilation and vesiculation of rough endoplamic reticulum and polysome disaggregation occured. Protein and RNA levels and the activity of several enzymes such as lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase and glucose 6-phosphate dehydrogenase of tryptophan administered group were significantly lower than those of control group suggesting that the tryptophan administration depressed protein biosynthesis resulting in the decrease of enzyme activity. It was found that serotonin content of egg yolk which has been incubated for 10 days were as much as three times that of control egg yolk. It is not clear whether the increase of serotonin content might inhibit intracellular yolk granule degradation which might result in malformation of chick embryo, but it is likely that tryptophan administration might depress protein biosynthesis, consequently, the enzyme biosynthesis would be impaired. This might give rise to improper development of chick embryo.

• The Korean Journal of Zoology
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• v.28 no.4
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• pp.257-278
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• 1985

The effect of aromatic amino acids such as phenylalaine, tryptophan and tyrosine on somitogenesis at the early stage of chick embryo has been investigated morphologically using light and electron microscopy. Micrographs of aromatic amino acid injected chick embryo showed that an incomplete somite segmentation occurred and some decremental effect on the nervous system were observed. Somites were poorly developed and their size were variable. Electron micrograph of somatic cells from aromatic amino acid injected chick embryo showed that chromatins were coagulated, some of mitochondria were damaged, and nucleus were transformed considerably in some cases. The protein and nucleic acid levels and some enzyme activities of 15-day chick embryo which received the injection of 1mg of aromatic amino acid in 0.05 ml of saline 24 hours after the incubation were analyzed. Protein, DNA and RNA levels of the test group were not lowered significantly but the activities of enzymes for basic metabolism, such as lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase and glucose 6-phosphate dehydrogenase were considerably lowered as compared with those of control. From the present expeerimental results, it was tentatively suggested that the administration of amino acid might slow down the yolk granule degradation probably by feed back mechanism resulting in the disturbance of amino acid balance in the cell, which might give rise to impair normal metabolic pattern leading to abnormal somitogenesis to chick embryo at very early stage of development.

• Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.5.1-5.7
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• 2016

The study was conducted to know the cyclic changes in gonadal maturation and to investigate the developmental stages of oocytes and testicular germ cells of an air-breathing fish, Channa striata. Fish were sampled monthly from lentic and lotic environments of three geographical locations of Bangladesh from December to November and the histological analysis of their gonad was done to evaluate the objectives. The highest mean GSI was $5.95{\pm}0.20$ for female in July and $0.14{\pm}0.01$ for male also in July showing that the gonadal development reached its peak during this month. The highest mean oocyte diameter was $1257.50{\pm}24.17{\mu}m$ observed in July implying that the oocyte reached maturity in this month. Histological study of ovary revealed the evidence of early yolk granule stage and late yolk granule stage from April to July. In case of male four stages of spermatogenesis were distinguished and spermatozoa were highly abundant in June and July. So the monthly pooled values of GSI and the analysis of gonadal histology indicated that the peak breeding season of C. striata occurred in July in the lentic and lotic environments. Samples collected from lentic and lotic habitats are suggestive of no difference in the development of the gonad. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. striata in its natural habitat.