七星瓢虫卵子发生的观察

对七星瓢虫(Coccinella septempunctata L.)卵子发生过程进行了组织学、细胞学观察及阶段划分,并与取食人工饲料的瓢虫进行对比。卵母细胞仅出现在幼虫期。蛹期已分化为卵母细胞与营养细胞。成虫期卵子发生可以明显的分为卵母细胞分化、卵母细胞营养及卵母细胞卵黄形成三个时期,并分为9个阶段。第1阶段:卵母细胞位于卵原区,进行第一次减数分裂的前期。第2阶段:卵母细胞位于颈区,开始增大,出现了营养索,DNA呈明显的孚尔根正反应。第3阶段:卵母细胞形成卵泡囊并进入生长区,核增大成胚泡。第4阶段:胚泡移至卵质周缘,卵质中RNA丰富,滤泡细胞立方形。第5阶段:胚泡内核仁增大、分枝并释放核仁小体进入卵质。第6阶段:营养索消失,滤泡细胞扁平并出现空位,卵黄形成开始。第7阶段:卵黄球形成逐渐充满卵质,胚泡膜逐渐消失。第8阶段:胚泡消失,滤泡细胞开始分泌卵壳。第9阶段:卵发育完成,经过上皮塞进入输卵管。取食人工饲料瓢虫的卵子发生过程显著缓慢,发育中的卵母细胞致量少,滤泡细胞及卵黄分布均不正常。     

短额负蝗卵子发生过程中糖复合物的动态分布

以生物素标记的凝集素(UEA-I、SBA、PNA)为探针,利用凝集素组织化学方法对短额负蝗(Atracto-morphasinensis)卵子发生过程中滤泡细胞和卵母细胞内糖复合物的分布进行了定位研究。结果表明,在卵子发生的各期滤泡细胞和卵母细胞中没有UEA-I受体的表达,SBA和PNA受体以不同的分布模式呈阶段性表达。两者首次出现于卵母细胞生长期,随后PNA受体消失,SBA受体大量表达;在卵黄形成期前期SBA受体和重新出现的PNA受体表达于卵黄颗粒形成部位,卵黄形成期后期两者均为阴性表达;成熟卵子中两种受体又以不同程度重新出现于卵黄膜。两种受体在滤泡细胞内均大量表达。提示,N-乙酰半乳糖胺和半乳糖-β-(1,3)半乳糖胺复合物的修饰和变化与卵母细胞的发育、卵黄物质的形成及滤泡细胞的增殖分化密切相关,卵黄膜上的糖复合物可能与精卵识别有关。     

短额负蝗卵子发生过程中糖复合物的动态分布

以生物素标记的凝集素(UEA-I、SBA、PNA)为探针，利用凝集素组织化学方法对短额负蝗(Atractomorpha sinensis)卵子发生过程中滤泡细胞和卵母细胞内糖复合物的分布进行了定位研究。结果表明，在卵子发生的各期滤泡细胞和卵母细胞中没有UEA-I受体的表达，SBA和PNA受体以不同的分布模式呈阶段性表达。两者首次出现于卵母细胞生长期， 随后PNA受体消失，SBA受体大量表达；在卵黄形成期前期SBA受体和重新出现的PNA受体表达于卵黄颗粒形成部位，卵黄形成期后期两者均为阴性表达；成熟卵子中两种受体又以不同程度重新出现于卵黄膜。两种受体在滤泡细胞内均大量表达 提示，N-乙酰半乳糖胺和半乳糖-β-(1，3)半乳糖胺复合物的修饰和变化与卵母细胞的发育、卵黄物质的形成及滤泡细胞的增殖分化密切相关，卵黄膜上的糖复合物可能与精卵识别有关。     

北京油葫芦卵子发生中DNA及RNA动态变化研究

用孚尔根及甲基绿 -派洛宁组织化学染色法了解北京油葫芦Teleogryllusmitratus(Burmeister)卵子发生各时期阶段中卵内DNA及RNA动态变化规律。在卵子发生的最初阶段 ,核中DNA的合成和复制最活跃 ,以后便慢慢减弱 ;而RNA则在第 2阶段合成最旺盛。在卵子发生各个阶段 ,滤泡细胞中DNA ,RNA均为阳性反应 ,并在卵细胞的卵黄形成期活动旺盛 ,为卵母细胞卵黄蛋白形成提供物质基础。卵子发生第 4～ 6阶段 ,滤泡细胞开放时期 ,血淋巴内一些物质可能直接或间接通过滤泡细胞间隙进入卵母细胞内 ,参与卵母细胞的发育和构建。研究表明卵子发生初期卵母细胞的发育和物质构建主要以内源性合成积累为主 ,中后期则有外源性物质的参与。     

斑翅蝗科四种蝗虫卵子发生阶段及种间差异的统计分析

通过组织学观察与测量对斑翅蝗科(直翅目,蝗总科)中4种蝗虫卵子发生各阶段进行测量和分析比较,4种蝗虫分别为:大垫尖翅蝗Epacromius coerulipes(Ivan.)、黄胫小车蝗Oedaleus infernalis Sauss.、花胫绿纹蝗Aiolopus tamulus(Fabricius)和疣蝗Trilophidia annulata(Thunberg).结果显示,在蝗虫卵子发生过程中,卵母细胞体积和形态变化显著,呈现指数增长模式;细胞核体积增长在发育初期增长显著,后期变化不显著;滤泡细胞体积和形态及数量呈现周期性变化规律;进而比较种间差异,可见不同种蝗虫的卵子发生存在不同的发育进程.     

家蝇的卵子发生的研究——Ⅰ.家蝇卵子发生过程

叙述了家蝇的卵子发生过程:根据卵室的形状与大小,卵室内卵母细胞的体积与营养细胞的比例,营养细胞核的变化,滤泡细胞的分化,边缘细胞的形成及卵壳形成等标准,将卵子发生分为了十一阶段,第一阶段在卵原区内,称为卵原囊,第二阶段为卵室形成,第三至第五阶段,卵室圆形,主要根据营养细胞核内染色体的形状划分,第六阶段卵室成椭圆形,并开始迅速生长;第七阶段卵母细胞占卵室四分之一,边缘细胞于此时发生。第八阶段卵母细胞占卵室三分之一,在营养细胞上的滤泡细胞开始退化至消失,营养细胞核出现灯刷染色体,第九阶段卵母细胞占卵室二分之一:第十阶段占四分之三,卵壳分泌形成,营养细胞开始退化。第十一阶段,营养细胞及滤泡细胞全部退化消失,形成卵。 描述了卵母细胞、营养细胞与核,滤泡细胞在发育各阶段中的变化,并讨论了其意义。     

刘氏蝎蛉卵巢管结构和卵子发生（英文）

卵巢管结构及卵子发生过程在探讨昆虫系统发育关系中有重要意义, 深入研究长翅目昆虫卵巢管结构及卵子发生可为确定其在全变态类昆虫中的系统发育地位提供依据。本文利用光学显微镜和扫描、透射电子显微镜技术研究了刘氏蝎蛉Panorpa liui Hua卵巢管超微结构及卵子发生过程。结果表明：蝎蛉卵巢由12根多滋式卵巢小管组成, 每个卵巢小管分为端丝、生殖区和生长区。根据滋养细胞、卵母细胞及滤泡细胞的变化, 卵子发生过程可分为5个阶段：卵黄发生前早期、卵黄发生前中期、卵黄发生前后期、卵黄发生期及卵壳形成期。在卵黄发生期, 滋养细胞为卵母细胞提供养分后逐渐消亡, 而此时的卵母细胞可通过滤泡之间的细胞间隙从血淋巴中获取营养。在卵壳形成期间, 3种不同类型的滤泡细胞参与形成不同区域的卵壳, 从而形成不同花饰的卵壳表面。据此推测, 与其他目的滋养细胞数目相比, 每个卵室中2次有丝分裂形成3个滋养细胞可能是比较原始的特征, 表明长翅目昆虫可能是全变态类群中近基部的分支。     

东方扁虾卵子发生的超微结构

根据卵细胞的形态、内部结构特征及卵母细胞与滤泡细胞之间的关系,东方扁虾的卵子发生可划分为卵原细胞、卵黄发生前卵母细胞、卵黄发生卵母细胞和成熟卵母细胞等四个时期。卵原细胞胞质稀少,胞器以滑面内质网为主。卵黄发生前卵母细胞核明显膨大,特称为生发泡;在靠近核外膜的胞质中可观察到核仁外排物。卵黄发生卵母细胞逐渐为滤泡细胞所包围;卵黄合成旺盛,胞质中因而形成并积累了越来越多的卵黄粒。东方扁虾卵母细胞的卵黄发生是二源的。游离型核糖体率先参与内源性卵黄合成形成无膜卵黄粒。粗面内质网是内源性卵黄形成的主要胞器。滑面内质网、线粒体和溶酶体以多种方式活跃地参与卵黄粒形成。卵周隙内的外源性物质有两个来源:滤泡细胞的合成产物和血淋巴携带、转运的卵黄蛋白前体物。这些外源性物质主要通过质膜的微吞饮作用和微绒毛的吸收作用这两种方式进入卵母细胞,进而形成外源性卵黄。内源性和外源性的卵黄物质共同参与成熟卵母细胞中富含髓样小体的卵黄粒的形成。卵壳的形成和微绒毛的回缩被认为是东方扁虾卵母细胞成熟的形态学标志。     

缠绕蚊蝎蛉雌性生殖系统构造及卵子发生

雌性生殖系统构造及卵子发生过程在探讨昆虫系统发育关系中具有重要意义。本文利用半薄切片法解剖观察了缠绕蚊蝎蛉Terrobittacus implicatus (HuangHua,2006)雌性生殖系统的构造及卵子发生过程。结果表明,缠绕蚊蝎蛉雌虫的卵巢由7根多滋式卵巢管组成,各个卵巢管的大小和长度不同。每个卵巢管可分为端丝、生殖区(原卵区)、生长区(卵黄区)和卵巢管柄4个部分。生长区由5到6个线形排列的卵室组成,每个卵室中有1个卵母细胞和3个滋养细胞。卵子发生可以分为3个时期,即卵黄发生前期、卵黄发生期、以及卵壳形成期。在卵子发生的整个过程中,卵母细胞、滋养细胞及滤泡细胞的形态均有明显变化。     

剑尾鱼卵子发生的组织学观察

应用光学显微镜对卵胎生硬骨鱼类剑尾鱼(Xiphophorus helleri)卵巢的组织结构进行了观察。结果显示,剑尾鱼卵子的发育过程可划分为6个时相。Ⅰ时相的卵母细胞呈原始分化状态,细胞外具一层细胞质膜。Ⅱ时相卵母细胞外不仅具有质膜,而且还包绕一层滤泡细胞。Ⅲ时相和Ⅳ时相的卵母细胞分化明显,胞质内开始积累脂滴和卵黄颗粒。Ⅴ时相为成熟卵子,卵子的卵膜极薄,胞质内含有丰富的脂滴和卵黄。Ⅵ时相卵母细胞进入退化期,滤泡细胞从卵周向中央突入,卵黄被完全吸收,滤泡细胞自身也变得肥大。结果表明,剑尾鱼卵巢中卵母细胞的发育是不同步的。     

中华蚱蜢卵子发生中花生凝集素受体的初步鉴定和发育表达

The distributions of PNA binding glycoconjugates in the plasma membrane of Acrida cinerea Thunberg germ cells were detected using biotin labeled PNA, for better understanding of the formation and changes of glycoconjugates during oogenesis. The ultrastructure of vitellogenesis also was observed by electron microscopy for detection of the origin and track of vitelline material. In the ovary, PNA receptors appeared in the oocyte cytoplasm of the second phases of oogenesis; positive granules gradually increased from the third phase to the fourth, and they exhibited a maximum expression before the vitellogennic stage in the cytoplasm of the oocyte. From the vitellogennic to chorionation stage, positive granules gradually declined. Binding sites on follicle cells were changed with their morphological variation in every stage of oogenesis. The vitelline of A. cinerea formed within the oocyte by degrees. The results suggest that PNA receptors and yolk materials are synthesized by the oocytc at an early period. With the development of the oocyte, some exogeous materials from two sources act as PNA receptors and others take part in vitelline synthesis. One is blood lymph that offers some useful materials to the oocyte directly through follicle cell gaps; the other are follicle cells that produce and transmit some materials to oocyte to support vitellogenesis. In addition, PNA receptors secreted by follicle cells participate in the formation of yolk membrane [ Acta Zoologica Sinica 5 l （5） ： 932 - 939, 2005 ].     

Structure of yolk granules in oocytes and eggs of Blattella germanica and their interaction with vitellophages and endosymbiotic bacteria during granule degradation

Oocytes and embryos of the cockroach Blattella germanica were examined by optical and electron microscopy to study yolk granule degradation during embryo development. During vitellogenesis, progressively larger yolk granules are formed in the ooplasm and by chorionogenesis, the mature granules are packed so tightly that their shape is highly distorted. Throughout ovarian development, endosymbiotic bacteria lie at the follicle cell/oocyte interface. Just prior to chorionogenesis the endosymbionts transit the oocyte plasma membrane and cluster at the periphery. Bacteria become more numerous over the ventral region of the egg by day 1 postovulation and begin to invade the interior of the yolk mass from the ventral periphery. At that time, lysis of the nearby yolk granules occurs while those in the central ooplasm remain intact and free of bacteria up to day 4. Vitellophages become evident by day 2 postovulation. These cells are also distributed over the egg's periphery but are most numerous in the ventral region. Vitellophages, in association with the endosymbionts, protrude toward the yolk granules and extend filo- and lamellipodia over the granule surface. Portions of the yolk granules are then engulfed and sequestered as large vacuoles in the vitellophage's cytoplasm. The vacuoles then become vesiculated. As embryo development proceeds, the vesiculated portions partition into smaller multivesicular bodies. This study describes the dynamics of yolk granule-vitellophage interaction in embryos of B. germanica and suggests that yolk utilization entails the cooperative efforts of both vitellophages and endosymbiont bacteria.     

Oogenesis in the leech Glossiphonia heteroclita (Annelida, Hirudinea, Glossiphoniidae) II. Vitellogenesis, follicle cell structure and egg shell formation

By the end of previtellogenesis, the oocytes of Glossiphonia heteroclita gradually protrude into the ovary cavity. As a result they lose contact with the ovary cord (which begins to degenerate) and float freely within the hemocoelomic fluid. The oocyte's ooplasm is rich in numerous well-developed Golgi complexes showing high secretory activity, normal and transforming mitochondria, cisternae of rER and vast amounts of ribosomes. The transforming mitochondria become small lipid droplets as vitellogenesis progresses. The oolemma forms microvilli, numerous coated pits and vesicles occur at the base of the microvilli, and the first yolk spheres appear in the peripheral ooplasm. A mixed mechanism of vitellogenesis is suggested. The eggs are covered by a thin vitelline envelope with microvilli projecting through it. The envelope is formed by the oocyte. The vitelline envelope is produced by exocytosis of vesicles containing two kinds of material, one of which is electron-dense and seems not to participate in envelope formation. The cortical ooplasm of fully grown oocytes contains many cytoskeletal elements (F-actin) and numerous membrane-bound vesicles filled with stratified content. Those vesicles probably are cortical granules. The follicle cells surrounding growing oocytes have the following features: (1) they do not lie on a basal lamina; (2) their plasma membrane folds deeply, forming invaginations which eventually seem to form channels throughout their cytoplasm; (3) the plasma membrane facing the ovary lumen is lined with a layer of dense material; and (4) the plasma membrane facing the oocyte forms thin projections which intermingle with the oocyte microvilli. In late oogenesis, the follicle cells detach from the oocytes and degenerate in the ovary lumen.     

Ultrastructural studies of differentiation in the oocyte of the polyclad turbellarian,Prostheceraeus floridanus

Oocyte differentiation in the polyclad turbellarian Prostheceraeus floridanus has been examined to determine the nature of oogenesis in a primitive spiralian. The process has been divided into five stages. (1) The early oocyte: This stage is characterized by a large germinal vesicle surrounded by dense granular material associated with the nuclear pores and with mitochondria. (2) The vesicle stage: The endoplasmic reticulum is organized into sheets which often contain dense particles. Vesicles are found in clusters in the cytoplasm, some of which are revealed to be lysosomes by treatment with the Gomori acid phosphatase medium. (3) Cortical granule formation: Cortical granules are formed by the fusion of filled Golgi vasuoles which have been released from the Golgi saccules. The association between the endoplasmic reticulum and Golgi suggests that protein is synthesized in the ER and transferred to the Golgi where polysaccharides are added to form nascent cortical granules. (4) Yolk synthesis: After a large number of cortical granules are synthesized, yolk bodies appear. They originate as small membrane-bound vesicles containing flocculent material which subsequently increase in size and become more compact. Connections between the forming yolk bodies and the endoplasmic reticulum indicate that yolk synthesis occurs in the ER. (5) Mature egg: In the final stage, the cortical granules move to the periphery and yolk platelets and glycogen fill the egg. At no time is there any evidence of uptake of macromolecules at the oocyte surface. Except for occasional desmosomes between early oocytes, no membrane specialization or cell associations are seen throughout oogenesis. Each oocyte develops as an independent entity, a conclusion supported by the lack of an organized ovary.     

Differential sorting of constitutively co-secreted proteins in the ovarian follicle cells of Drosophila

Conventional and freeze-fracture electron microscopy, immuno-electron microscopy of ovarian cryosections and confocal immunofluorescence were used to analyze the ovarian distribution of the major protein classes being secreted by the follicle cells during the vitellogenic and choriogenic stages of Drosophila oogenesis. Our results clearly demonstrated that at vitellogenic stages the follicle cells co-secrete constitutively vitelline membrane and yolk proteins that are either sorted into distinct secretory vesicles or they are segregated in different parts of bipartite vesicles by differential condensation. Following their exocytosis only the vitelline membrane proteins are incorporated into the forming vitelline membrane. The yolk proteins (along with their hemolymph circulating counterparts) diffuse through gaps amongst the incomplete vitelline membrane and are internalized through endocytosis by the oocyte where they are finally stored into modified lysosomes referred to as alpha-yolk granules. The unexpected immunolocalization of vitelline membrane antigens in the associated body of the alpha-yolk granules may indicate that this structure is a transient repository for the proteins being internalized into the oocyte along with the yolk proteins. In the early choriogenic follicle cells the vitelline membrane and early chorion proteins were found to be co-secreted and to be evenly intermixed into the same secretory vesicles. These findings illuminate new details concerning the follicle cells secretory and oocyte endocytic pathways and provide for the first time evidence for condensation-mediated sorting of constitutively secreted proteins in Drosophila.     

Ultrastructural study of oogenesis in Phoronopsis harmeri (Phoronida)

Temereva, E.N., Malakhov, V.V. and Yushin, V.V. 2011. Ultrastructural study of oogenesis in Phoronopsis harmeri (Phoronida). —Acta Zoologica (Stockholm) 92 : 241–250. The successive stages of oogenesis in Phoronopsis harmeri were examined by electron microscopy methods. During the oogenesis, each oocyte is encircled by vasoperitoneal (coelomic) cells forming a follicle. The previtellogenic oocytes are small cells which accumulate ribosomes for future synthesis; their cytoplasm contains characteristic clusters of mitochondria and osmiophilic particles resembling a germ plasm of other metazoans. The cytoplasm of the vitellogenic oocytes includes numerous mitochondria, cisternae of the rough endoplasmic reticulum, Golgi bodies and annulate lamellae. The synthesis of three types of inclusions was observed: strongly osmiophilic granules (lipid droplets) as a prevalent component, distinctly larger granules surrounded by membrane (proteinaceous yolk) and numerous large vesicles with pale flocculent content. No inclusions which could be unequivocally interpreted as the cortical granules were detected. The surface of the vitellogenic oocytes is covered by microvilli which increase in number and length during development. The oogenesis in Phoronida may be interpreted as follicular because of close association of oocytes with the vasoperitoneal tissue. However, well‐developed synthetic apparatus together with a strongly developed microvillous surface and absence of endocytosis indicate a clear case of autosynthetic vitellogenesis. Thus, in phoronids, there is a combination of simply developed follicle and autosynthesis that, apparently, is plesiomorphic character.     

Development and fine structure of the yolk nucleus of previtellogenic oocytes in the medaka Oryzias latipes

The development and fine structure of yolk nuclei in the cytoplasm of previtellogenic oocytes were examined by electron microscopy during several stages of oogenesis in the medaka, Oryzias latipes. Shortly after oogenesis starts, oocytes 20-30 microm in diameter have much electron-dense (basophilic) cytoplasm, within which a continuous or discontinuous, irregular ring-shaped lower electron-dense area of flocculent appearance (LF) begins to emerge around the nucleus. The yolk nucleus is first recognized within an LF area as a few fragments of dense granular thread measuring 20-25 nm in width. The threads consist of two rows of very dense granules resembling ribosomes or ribonucleoprotein (RNP)-like particles in size and electron density. These thread-like fragments gradually increase in number and length until they assemble into a compact, spherical mass of complicated networks. Analysis of serial sections suggests that the yolk nucleus is a complicated mass of numerous, small deformed vacuoles composed of a single lamella with double layers of ribosomes or RNP-like granules, rather than a mass of granular threads. When oocytes develop to greater than 100 microm in diameter, the yolk nucleus begins to fragment before dispersing throughout the surrounding cytoplasm, concomitantly with the disappearance of LF areas. At this stage of oogenesis, a restricted region of the granulosa cell layer adjacent to the yolk nucleus becomes somewhat columnar in morphology, fixing the vegetal pole region of the oocyte.     

Follicular epithelial cell apoptosis of atretic follicles within developing ovaries of the mosquito Culex pipiens pallens

Follicular atresia, the degeneration of developing follicles, is always incident to normal oogenesis in both oviparous and viviparous animals. Photo- and electron-microscopic observation of degenerating follicles within developing ovaries taken from blood-fed Culex pipiens pallens mosquitoes showed gradual degradation of the internal structures including yolk granules in the oocyte. The epithelial cells, which sometimes incorporated yolk granules from the oocyte along with the shrinkage of the follicle, gradually lost their uniform columnar shape, while their integrity as a covering layer remained. In situ active caspase analysis detected active enzymes in these epithelial regions. In the latest stages of atresia where either the nurse cells or oocyte were lost, the follicle was mainly comprised of irregularly shaped epithelial cells, and some of these cells' nuclei contained condensed chromatin peripherally, one of the characteristics of apoptotic cells. Also terminaldeoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling treatment indicated that DNA fragmentation occurred in these follicles. It seems likely that in atretic follicles the epithelial cells survive to play key roles in the event, and then finally undergo their own apoptotic cell death so as to give the developmental site to the next follicle in the same ovariole.     

An ultrastructural study of oogenesis in a marine triclad

The ultrastructural features of oocyte differentiation were studied in the marine triclad Cercyra hastata. Oocytes at several stages of maturation, each surrounded by follicle cell projections, are present within each of the two ovaries. A pre-vitellogenic and a vitellogenic stage have been detected in the oogenesis of C. hastata. The pre-vitellogenic stage is mainly characterized by an increase in the nuclear and nucleolar volume and activity, and the appearance and development of cortical granule precursors which are elaborated by the Golgi complex. In early phases of the vitellogenic stage, intense delamination and blebbing of the nuclear envelope occurs which probably contributes to an increase in number of cytoplasmic membranes and to transfer of nuclear material to the cytoplasm. The rough endoplasmic reticulum is extensively developed and often assumes a ‘whorl’ array. Several areas of yolk precursor formation appear in the whorls. Numerous 2–5 μm protein yolk globules are subsequently formed which appear surrounded by a double membrane (cisternae of the smooth endoplasmic reticulum) and become randomly distributed throughout the cytoplasm of mature oocytes. The peripheral ooplasm is occupied by a monolayer of electron-dense cortical granules. Finally, the evolutionary significance of the autosynthetic mechanism of yolk production is discussed.