• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1031-1040
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• 2015

Ultrstructural studies of germ cell differentiation and vitellogenesis in the oocytes of the female Rapana venosa in the brackish water area of Seomjin River were investigated by transmission electron microscope observations. In the early vitellogenic oocytes, the Golgi complex and mitochondria were involved in the formation of glycogen particle, lipid droplets, and yolk granules. In the late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in the cytoplasm. However, heterosynthetic vitellogenesis in this species were not observed in vitellogenic oocytes during oogenesis. A mature yolk granule was composed of three components: crystalline core, electron lucent cortex and the limiting membrane. As shown in some large gastropods, vitellogenesis in R. venosa occurred by way of endogenous autosynthesis without heterosythetic vitellogenesis (exogeneous endocytosis), which are found in the oocytes in bivalves. The mating period and spawning activity were related with the increases of seawater temperatures and salinities.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.145-151
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• 2009

The ultrastructural changes in germ cells during oogenesis of the melania snail, Semisulcospira libertina libertina have been investigated by light and electron microscopy. The ovary is located on the surface of the hepatopancreas in the spiral posterior region. The ovary exhibited greenish color in the gonadal mature season. The ovary was composed of a number of oogenic follicles. Oogenesis was divided into five stages with histological features: (1) oogonia, (2) previtellogenic, (3) initial vitellogenic, (4) active vitellogenic, and (5) mature stages. Oogonia were oval in shape, $4-6\;{\mu}m$ in diameter, and had a large nucleus. Previtellogenic oocytes were about $20\;{\mu}m$ in diameter and the cytoplasm reacted with hematoxylin in H-E satin. Initial vitellogenic stage, oocytes were $60-80\;{\mu}m$ in diameter, and small yolk granules of low electron density are scattered in the cytoplasm. Oocytes in the initial vitellogenic stage were connected with ovarian follicle by egg stalk. Active vitellogenic oocyte were $100-120\;{\mu}m$ in diameter. Electron density, size and quantity of yolk granules that are distributed in the cytoplasm have increased from the previous stage. Result of TEM observations, the oocyte contains well-developed Golgi complex, endoplasmic reticula and tubular mitochondria in the cytoplasm. Cytoplasm of mature oocyte was filled with proteinaceous yolk globules of high electron density. In this stage, the length of microvilli in the egg envelope was approximately $1.1\;{\mu}m$.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.78-78
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• 2001

본 연구는 초자화동결법(vitrification)을 이용하여 미성숙 소 난포란의 동결기술을 개발하기 위하여 시도하였으며 난포의 크기와 동결보호제의 농도 및 난황의 첨가가 동결-융해 후 미성숙 소 난포란의 생존성에 미치는 영향을 조사하였다. 미성숙 난자는 3mm 미만과 3mm 이상으로 구분된 난포로부터 채란하였으며 동결처리 전 동결보호제로서 30%EG과 40%EG, 그리고 각각에 10%의 egg yolk을 첨가하여 동결-융해 후 미성숙 난자의 생존성과 체외성숙율 및 체외수정율을 비교하였다. 생존율과 성숙율에 있어서 3m 미만과 3mm 이상의 2 처리구 모두 40%EG에 10%의 egg yolk을 첨가할 경우 유의적으로 높은 결과를 보였으나 3mm이하에서는 EG수준과 egg yolk 첨가 유무간에 생존율과 성숙율에 유의적인 차이가 나타나지 않았다. 동결-융해 후 체외수정율은 3mm 미만에서는 처리구간에 유의적인 차이를 보이지 않았으나 3mm이상의 경우에서는 40%EG에 10%의 egg yolk 첨가구가 다른 처리구에 비해 유의적으로 높았다. 난포의 크기에 따른 동결-융해 후 생존율은 3mm미만의 난포란이 3mm이상 보다 높았으나 성숙율과 수정율에 있어서는 3mm이상이 3mm미만의 난포란에서 보다 다소 높았다. 생존율, 성숙율 및 수정율 모두 난포크기간에 유의차는 인정되지 않았다.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.179-184
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• 2014

A histological study on the egg envelope and oogenesis of Gobiobotia brevibarba (Pisces, Cyprinidae) was carried out by a light microscope and a scanning electron microscope. Various developmental cells appeared in the ovary caught during May 2014, spawning season. For the relative area of oocyte, the ovary consisted of mature stage (74.5%), a vitellogenic stage (yolk granule stage, 16.6% and yolk vesicle stage, 6.6%) and previtellogenic stage (perinucleolus stage 2.2%), which means its spawning season. The cytoplasm of the perinucleolus oocyte is acidic and many nucleoli are located at the inner side of the nuclear membrane. The yolk vesicles, an early vitellogenic stage, has a follicular layer and a zona radiata clearly. Numerous villi, called an egg envelope, begin to form on the zona radiata. The yolk granules, an another vitellogenic stage, proceeds and they show a strong eosinophilic nature. Such yolk granules appeared between the yolk vesicles occupying most cytoplasm, and as the stage proceeds, there are some yolk masses fused with each other. Egg envelope is covered with plenty of villi ($2{\sim}3{\mu}m$ in the length) over the entire egg surface.

• The Korean Journal of Zoology
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• v.31 no.4
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• pp.318-326
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• 1988

여포세포에서 합성된 난황단백질이 난모세포로 이동하는 동안에 난황체가 이 두 종류의 세포사이에 형성되었다가 결국은 난황막으로 전환한다. 단계7까지는 뚜렷하게 보이던 난모세포막과 여포세포막이 소멸되고 그 자리에 전자 밀도가 높은 난황체 물질이 산만하게 축적된다. 난황체는 단계9에서 막성 구조의 일종인 linkage bridge로 둘러싸여 단계11까지는 두께가 5∼7um가 되리 만큼 성숙한다. 단계13에서 난황체는 비로소 난황막으로 전환되는데, 이때 난황막의 두께는 겨우 1 U m에 지나지 않는다. 이러한 두깨의 감소는 난황체 물질이 다량 난모세포 쪽으로 이동한 것으로 생각 되었다. coated vesicle을 포함한 다양한 종류의 과립이 난황체 양쪽에서 관찰되었는데, 난모세포쪽에 출현한 과립은 난황체 물질이 난모세포로 이동되는 구조로 해석되었고 여포 세포쪽에서 관찰된 과립은 주로 난황체의 전자밀도와 동일한 점으로보아 여포세포에서 합성되어 난황체를 형성하는 물질로 이루어진 구조로 해석되었다. As yolk proteins are transported from !he follicle cells into oocvtes, vitelline body forms and changes into a vitelline membrane between the ko celt types during the vitellogenic period. Cell membranes of oocyte and follicle cells surrounding the oocyte disappear at stage 7 and high electron-dense substance of vitelline body simultaneously accumulates sporadically between the cell types. The vitelline body becomes surrounded by linkage bridge, a membranous structure, at stage 9 and greatly increases in thickness to be 5-7 U m thick at stage 11. At stage 13 the vitelline body becomes vitelline membrane, which is now only 1 U m thick, suggesting that much of the substance of the vitelline body has been transported into oocyte. Various types of vesicles including coated vesicles were observed at both sides of th vitelline body. The vesicles occurred at the side of oocyte were interpreted to be structures transported from the vitelline body into oocyte, whereas those found at the side of the follicle cells were thought to be structures made in the follicle cells and fused into the vitelline body.

• The Korean Journal of Malacology
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• v.32 no.1
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• pp.17-23
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• 2016

Ultrastructural studies of oocyte development and vitellogenesis associated with the follicle cells in female Phacosoma japonicus were investigated by electron microscope observations. Vitelloogenesis in the oocytes occured by way of endogenous autosynthesis and exogenous heterosynthesis: vitellogenesis occurred through a process of endogenous autosynthesis, which involves a combined activity of the Golgi complex, rough endoplasmic reticulum, and mitochondria. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors into the basal region of the early vitellogenic oocytes. In this study, follicle cells, which attached to the previtellogenic and vitellogenic oocytes, were easily found. In particular, the follicle cells were involved in the development of previtellogenic oocytes by the supply of nutrients, and vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors. The functions of follicle cells, which attached to mature oocytes, accumulate reserves of lipid granules and glycogen particles for vitellogesis in the cytoplasm of the follicle cells.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.08a
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• pp.36-37
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• 2001

큰가리비는 자웅이체이다. 난환형성과정은 난모세포의 발달정도에 다라 다르게 나타나고 있다. 난자형성과정은 난원세포기, 전난황형성난모세포기, 초기난황형성난모세포기, 후기난황형성난모세포기, 성숙난모세포기의 연속적인 5단계의 과정으로 나눌 수 있었다. 전난황형성기 난모세포질 내에서는 핵주변 구역에 골지장치와 수많은 공포들 및 미토콘드리아들이 출현하고 있는데 이들은 차후, 지방적 형성에 관여한다. 난황형성전기난모세포(previtellogenic oocyte)에서는 지방적 및 지질과립들이 핵막 근처에서 출현하여 피질층쪽으로 분산되는 반면, 같은 발달 단계의 난모세포질의 피질구역에서는 피질과립들(단백질성 난황과립)이 처음으로 생성되어 난황막 근처의 피질층에서 핵주변 구역쪽으로 분산.분포된다. 난황형성후기 난모세포에서는 세포질 내의 골지장치, 공포, 미토콘드리아, 그리고 조면소포체들이 자율합성에 의해 난황과립 형성에 관여하고 있다. 반면 외인성 물질들인 지질형태의 과립들, 다량의 글리코겐 입자들이 생식상피 내에서 출현하고 있는데. 이들 물질이 생식상피에서 난황막 구조물인 미세융모를 통해 난황형성 후기 난모세포의 날질 내로 통과해 들어가는 현상이 관찰되었다. 이와같은 현상은 난황형성이 일어날 때에 heterosynthesis가 일어나고 있음을 시사한다. 완숙난모세포의 난경은 약 50~60$\mu\textrm{m}$이다. 정자형성과정은 정원세포기, 제1차정모세포기, 제2차정모세포기, 정세포기, 정자기의 연속적인 5단계로 나눌수 있었다. 정셍포기에서 정자로 변태되는 과정 중에 침체의 분화과정이 있는데 이에는 1. Golgi phase, 2. Cap phase 3. acrosome phase, 4. maturation phase의 단계를 거쳐 첨체가 완성된다. 정자는 원시적 형태를 이루고 있으며 4개의 미토콘드리아가 부핵을 형성하고 있다. 완숙정자 두부의 길이는 대략 $3 \mu$m 이며, 미부의 길이는 약 $30 \mu$m정도이다. 정자 미부편모의 axoneme은 중앙의 2개의 미세소관(microtubule)과 주변에 위치한 9개의 2중 미세소구관(microtublue)으로 이루어져 있다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.76-90
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• 1993

To clarify the relations between photoperiodism and x-organ of eyestalks to the control of gonadal maturation in a freshwater prawn, Macrobrachium nipponense, the present investigation was performed with following examinations: 1) the influence of water temperature and daylength on the control of gonadal maturation, 2) the effect of eyestalk ablation on the gonadal maturation, 3) the seasonal variation of histology of MEX-organ (medulla externa X-organ) in the eyestalk. In previtellogenesis period (December${\sim}$March) and vitellogenesis period (April${\sim}$May), gonadal maturation was considerablely influnced by water temperature. In these periods, GSI increased and gonads were matured with water temperature rising without regard to photoperiod conditions (12L/12D and 15L/9D). In spawning period (June${\sim}$August), however, gonadal maturation was influenced by photoperiod condition. While high value of GSI was kept at long photoperiod regime (15L/9D), GSI was decreased at short photoperiod regime (12L/12D). In resting period (September${\sim}$November), no rematuration was occurred at all the experimental regimes combinated with water temperatures ($16^{\circ}C,\;22^{\circ}C,\;28^{\circ}C$) and photoperiod (12L/12D, 15L/9D). Effect of X-organ which inhibite the gonadal maturation was stronger in resting period than that in previtellogenesis and ealy spawning periods by observations on the effectiveness of eyestalk ablation on the gonadal maturation. In MEX-organ of eyestalk, the number of neurosecretory cells of which size was over $20{\mu}m$ in diameter varied according to the reproductive cycle. The number of cells increased $77{\pm}12$ in resting period, and decreased $55{\pm}7$ in vitellogenesis period. Volume of Bellonci's organ, however, increased in vitellogenesis period in comparison with that in resting period.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.209-216
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• 2007

The ovarian structure and ultrastructural changes in germ cells during oogenesis of the spiny top shell, Batillus cornutus, have been investigated by light and electron microscopic observations. Specimens of the spiny top shell were collected from the subtidal zone of Wando, south coast of Korea. Spiny top shell was dioecious. The ovary was located on the surface of the hepatopancreas in the spiral posterior region. The ovary had greenish color in the gonadal mature season. The ovary comprised many ovarian lobules, and the ovarian lobule consisted of connective mesenchymal tissue and epithelial cells. Oogonium had a large nucleus with nucleolus of high electron density. In previtellogenic oocyte, small yolk granules of low electron density were scattered in the cytoplasm. Oocytes in the initial vitellogenic stage were connected with the ovarian lobule by egg stalk. The result of TEM observations showed that initial vitellogenic oocyte contained well-developed Golgi complex, endoplasmic reticula, tubular mitochondria and numerous yolk granules of various electron densities and sizes. The electron density, size and quantity of yolk granules which were distributed in the active vitellogenic oocyte were increased compared to the previous stage. Thickness of egg envelope in the late active vitellogenic oocyte was approximately 4.4 $[\mu}m$. Cytoplasm of ripe oocyte was filled with proteid yolk globules of high electron density and lipid yolk globules of low electron density. In this stage, the thickness of egg envelope was approximately 6.5 ${\mu}m$.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.140-146
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• 1995

Changes in protein content during oocyte development was measured and egg-specific protein was characterized from the eggs in Lucilia illustris. During normal development ovarian protein was rapidly increased at 72hr and reached maximum at 96hr after a protein meal, when the eggs were fully matured. Purified protein from the ovaries by gel filtration of DEAE-cellulose an Sephacryl S-200 was loaded on 7.5% native polyacrylamide gel electrophoresis and identified at ${R}_{f}$ 0.4 as egg-specific protein, which has a mol. wt of 110,000. A total of 13 amino acids in th egg-specific protein was identified and expecially asparagine, glutamic acid, and tyrosine were highly concentrated. Five fatty acids were also identified. It is suggested that there is a specific protein in the eggs of L. illustris except yolk protein synthesized and secreted by fat body.