• 한국동물학회지
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• 제22권1호
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• pp.26-38
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• 1979

In recent years some very substantial advances have been made in our understanding of oogenesis as a result of studies on a relatively few, very diverse species of animals. In this lecture I will (1) outline normal oogenesis using an advanced insect, Drosophila melanogaster, as an example, (2) show how oogenesis can be dissected genetically by studying the ovarian pathologies of flies homozygous for various recessive, female sterile genes, and (3) discuss how estimates can be made of the fraction of the Drosophila genome devoted to oogenesis. Then I will describe studies on mutations that block vitello-genesis in Drosophila and indicate what they tell us about inter actions between the ovary, the fat body and the endocrine system. I will next discuss the evolutionary mechanisms that have been adopted in higher insects and amphibians to produce the prodigious quantities of ribosomes stored in oocytes. I will end with an account of the results of recent stuides on amphibian lampbrush chromosomes which show how messenger RNAs are transcribed during oogenesis.

• 한국패류학회지
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• 제30권4호
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• pp.333-342
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• 2014

Ultrastructural studies of oogenesis in oocytes, oocyte degeneration associated with the follicle cells in female Coecella chinensis were investigated for clams collected from Namhae, Geongsangnam-do, Korea. In this study, vitellogenesis during oogenesis in the oocytes occured by way of endogenous autosynthesis and exogenous heterosynthesis. Of two processes of vitellogenesis during oogenesis, the process of endogenous autosynthesis involved the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum. whereas the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors at the basal region of the oolema of the early vitellogenic oocytes prior to the formation of the vitelline coat. It is assumed that the follicle cells were involved in the development of previtellogenic and early vitellogenic oocytes and appear to play an integral role in vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors, and also they were involved in oocyte degeneration by assimilating products originating from the degenerated oocytes, thus allowed the transfer of york precursors needed for vitellogenesis (through phagocytosis by phagolysosomes after spawning). Follicle cells presumably have a lysosomal system for breakdown products of oocyte degeneration. and for reabsorption of various phagosomes (phagolysosomes) in the cytoplasm for nutrient storage during the period of oocyte degeneration.

• Applied Microscopy
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• 제20권2호
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• pp.117-126
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• 1990

Structural changes of the vitelline envelopes during oogenesis of a polychaete, Nectoneanthes oxypoda, were examined with a scanning electron micrscope. Oocytes grow in the same coelomic fluid to the final stage, but the surface appears to change in the structure during oogenesis. Projections, which were identified to be microvilli, change in shape, number and size. Short microvilli, which cover the surface of oocyte of $33{\mu}m$ diameter densely, grow in length, reaching a maximum at the stage of $73{\mu}m$. The number of microvilli increases with the stages of oogenesis, reaching a plateau at the stage of $82{\mu}m$. The observations suggest that control of material transport including yolk precursor proteins may be correlated with the structural changes in the microvilli.

• 한국어류학회지
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• 제29권4호
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• pp.252-257
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• 2017

잉어목 모래무지아과에 속하는 한국 고유종 돌마자 Microphysogobio yaluensis 난소 내 생식세포들의 형태학적 특징을 연구하기 광학현미경을 이용하여 조사하였다. 난자형성과정 (oogenesis)은 크게 염색인기 (chromatin-nucleolus stage), 주변인기(peri-nucleolus stage), 난황형성기(vitellogenesis)의 난황포 및 난황구기와 성숙(mature stage)의 단계로 구분되었다. 염색인기에는 배포가 크게 형성되며 실모양의 염색질이 산재되어 있다. 주변인기에는 핵 내에 산성의 인들이 핵막인근에 분포하고 있었으며, 난막(egg envelope)이 형성되기 시작하였다. 이후 난황형성기의 난황포 단계에서는 세포질의 대부분이 텅빈 공포모양의 난황포로 구성되며, 발생이 진행되면서 난황구 단계에서는 난황포 사이에 eosin에 염색되는 난황과립으로 대체되었다. 성숙단계에 도달한 난세포에는 많은 난황구들이 하나의 커다란 난황괴(yolk mass)를 형성하고 있었다. 이 시기의 난세포의 난막은 세포질과 여포세포층 사이에 얇게 형성되었다.

• 한국발생생물학회지:발생과생식
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• 제20권3호
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• pp.227-235
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• 2016

Ultrastructural studies on oocyte development and vitellogenesis in oocytes, and the functions of follicle cells during oogenesis and oocyte degeneration were investigated to clarifyb the reproductive mechanism on vitellogenesis of Scapharca subcrenata using electron microscope observations. In this study, vitellogenesis during oogenesis in the oocytes occured by way of autosynthesis and heterosynthesis. Of two processes of vitellogenesis during oogenesis, the process of endogenous autosynthesis involved the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors at the basal region of the oolema of the early vitellogenic oocytes before the formation of the vitelline coat. 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. Based on observations of follicle cells attached to degenerating oocytes after spawning, follicles of this species are involved in lysosomal induction of oocyte degeneration for the resorption phagosomes (phagolysosomes) in the cytoplasm for nutrient storage, as seen in other bivalves. In this study, the functions of follicle cells can accumulate reserves of lipid granules and glycogen particles for vitellogenesis from degenerating oocytes after spawning.

• Applied Microscopy
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• 제15권1호
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• pp.86-100
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• 1985

A observation of the ovarian development and oogenesis of Pieris rapae Linne has been carried out during metamorphosis using stereo-microscope, light microscope and electron microscope. The results obtained through this experiment are as follows: 1. The ovarian development and vitellogenesis begin at the 3-day old pupa and the 6-day old pupa respectively, and the adult ovary right after their emergence contains a few mature eggs. 2. The species described above are further observed at six different stages in oogenesis, and the results are summarized as follows. 1) Pieris rapae has polytrophic ovarioles. The cell organelles of the nurse cells are transfered to the oocyte through the ring canal at the early oogenesis. 2) At stage 2, the nuclear envelope of oocyte nucleus is less infolding than that of nurse cell nucleus. In the oocyte cytoplasm a large number of ribosomes are observed. 3) At stage 3 and 4, many micropinocytotic vesicles are observed in the oocyte cytoplasm. These vesicles are fused together to form large proteid yolks. 4) At stage 5, the vitelline membrane is laid down in the intercellular space between the follicle cells and oocyte. 5) At stage 6, the chorion is formed by the follicle cells. 6) A micropyle and a number of aeropyle are observed on the surface of a mature egg.

• Animal cells and systems
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• 제14권4호
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• pp.343-349
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• 2010

Ultrastructural studies of vitellogenesis in oocytes and follicle cells during oogenesis in female Protothaca (Notochione) jedoensis were investigated by histological and transmission electron microscope observations. In early vitellogenic oocytes, combined activities of the Golgi complex, mitochondria and rough endoplasmic reticulum in the cytoplasm are associated with autosynthetic vitellogenesis. Furthermore, at this time, many coated vesicles at the basal region of the oolemma of the oocyte lead to the formation of vesicles through endocytosis in the cytoplasm. Through the formation of the coated pits on oolemma during vitellogenesis, the uptake of extrafollicular precursors (nutritive materials) occurs in coated vesicles by endocytosis. Therefore, it is assumed that these exogenous materials are involved in heterosynthetic vitellogenesis. During late oogenesis, exogenous yolk precursors (yolk granules), lipid droplets and proteinaceous yolk granules are present in the cytoplasm of late vitellogenic oocytes. In mature oocytes, small yolk granules appear intermingled and form large mature yolk granules. Thus, two processes of vitellogenesis occur in oocytes by way of endogenous autosynthesis and exogenous heterosynthesis. The follicle cells attached to the oocytes appear to play an integral role in vitellogenesis in this study.

• 한국패류학회지
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• 제22권1호
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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).

• 한국동물학회지
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• 제22권2호
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• pp.43-53
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• 1979

管棲 갯지렁이(Schizobranchia insignis)의 卵子形成 및 初期發生 期間에 일어나는 단일유전자 발현의 변이에 대하여 DNA-RNA 分子結合法을 이용하여 연구하였다. 卵子形成 初期에 活性化되었던 유전자의 일부는, 卵子形成 과정이 진행됨에 EK라 점차 억제되는 경향을 보였으며, 初期에 생성된 전사물질의 일부는 생성된 후, 卵子形成 과정에서 점차 소모되어, 末期에 잔존한 전사물질의 양은 사실상 初期에서 보다 적었다. 즉, 初期의 卵子는 末期에서는 존재하지 않는 단일유전자의 전사물질을 함유하고 있음이 확실하였다. 수정 후 발생단계를 통하여, 卵子形成 期間 중 발현된 유전자와는 다른 새로운 유전자의 발현이, Trochophore stage까지 계속 증가됨을 보여 주었다.

• 한국패류학회지
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• 제32권1호
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• pp.1-7
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• 2016

북방전복에서 난자형성과정 동안 생식세포는 조직학적 특징에 따라 난원세포 (oogonium), 난황형성전기 난모세포(previtellogenic oocyte), 난황형성개시기 난모세포 (initial vitellogenic oocyte), 난황형성초기활성기 난모세포 (early active vitellogenic oocyte), 난황형성후기활성기 난모세포(late active vitellogenic oocyte) 및 완숙기 난모세포 (ripe oocyte)로 구분할 수 있다. 난자형성과정 동안 난모세포, 핵 및 인의 크기는 증가하는 경향을 보였으나 핵에 대한 인의 크기 비율은 감소하였다. 난모세포 세포질의 염색성은 H-E 염색에서 호염기성에서 호산성으로 변하였다. 난자형성과정 동안 난모세포에서 난병과 젤리층의 외막이 발달되었다. 이러한 조직학적 변화는 난모세포의 난황축적 및 산란준비과정으로 판단된다.