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 ].     

泥螺卵子发生的超微结构研究

利用透射电镜观察了泥螺卵子发生过程。结果表明 ,泥螺的卵子发生可划分为卵原细胞、卵黄发生早期、卵黄发生中期及卵黄发生后期卵母细胞 4个时期。卵原细胞核大而圆 ,胞质内分布有少量的线粒体和高尔基囊泡 ,细胞表面具微绒毛。卵黄发生早期的卵母细胞 ,胞质中各类细胞器发达 ,并出现数量较多的类朦胧子。卵黄发生中期的卵母细胞胞体迅速增大 ,核伸出伪足状突起 ,卵质中各种细胞器活动活跃 ,并参与形成卵黄粒和脂滴。此期还可观察到卵母细胞与滤泡细胞间的物质交换现象。卵黄发生后期的卵母细胞体积增至最大 ,细胞器数量减少。本文就卵黄发生前后卵母细胞内部构造的变化、意义及滤泡细胞与卵母细胞蛋白来源间的关系作了探讨     

Distributional arrangement of mitochondria in the granulosa cells surrounding stage III zebrafish (Danio rerio) oocytes

Mitochondria play a vital role during oocyte maturation, fertilization, and embryo development. In this study, confocal microscopy with the mitochondrial membrane potential-sensitive dye JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl-carbocyanine iodide) was used to investigate mitochondria distribution and activity of stage III zebrafish ovarian follicles. To support the mitochondrial origin of the fluorescence obtained by JC-1, a second mitochondrial probe, MitoTracker Green FM, was used. Cryo-scanning and transmission electron microscopy were also used to validate the distribution and localization of mitochondria obtained by mitochondrial staining. The mitochondrial probes were unable to penetrate the oocyte, and as a result it was not possible to observe stained mitochondria in the oocyte cytoplasm. However, mitochondrial staining of the granulosa cell layer surrounding the stage III zebrafish oocyte exhibited a contiguous aggregation pattern of mitochondria. Cryo-scanning electron microscopy studies also showed the oocyte surface to be covered by polygonal patterns of ridges of the same dimensions as the distributional arrangement of mitochondria in the granulosa cells. Though the results suggested the need for defolliculation to assess mitochondrial distribution and activity in the stage III zebrafish oocyte cytoplasm, the findings of this study will contribute to our understanding of oogenesis and folliculogenesis processes in fish.     

Oogenesis in four species of Piscicola (Hirudinea, Rhynchobdellida)

Piscicola has a pair of elongated sac-shaped ovaries. Inside the ovaries are numerous small somatic cells and regularly spherical egg follicles. Each follicle is composed of three types of cells: many (average 30) germ cells (cystocytes) interconnected by intercellular bridges in clones (cysts), one intermediate cell, and three to five outer follicle cells (envelope cells). Each germ cell in a clone has one intercellular bridge connecting it to the central anucleate cytoplasmic mass, the cytophore. Each cluster of germ cells is completely embedded inside a single huge somatic follicle cell, the intermediate (interstitial) cell. The most spectacular feature of the intermediate cell is its development of a system of intracytoplasmic canals apparently formed of invaginations of its cell membrane. Initially the complex of germ cell cluster + intermediate cell is enclosed within an envelope composed of squamous cells. As oogenesis progresses the envelope cells gradually degenerate. All the germ cells that have terminated their mitotic divisions are of similar size and enter meiotic prophase, but one of the cystocytes promptly starts to grow faster and differentiates into the oocyte, whereas the remaining cystocytes withdraw from meiosis and become nurse cells (trophocytes). Numerous mitochondria, ER, and a vast amount of ribosomes are transferred from the trophocytes via the cytophore toward the oocyte. Eventually the oocyte ingests all the content of the cytophore, and the trophocytes degenerate. Little vitellogenesis takes place; the oocyte gathers nutrients in the form of small lipid droplets. At the end of oogenesis, an electron-dense fibrous vitelline envelope appears around the oocyte, among short microvilli. At the same time, electron-dense cortical granules occur in the oocyte cortical cytoplasm; at the end of oogenesis they are numerous, but after fertilization they disappear from the ooplasm. In the present article we point out many differences in the course of oogenesis in two related families of rhynchobdellids: piscicolids and glossiphoniids.     

A Balbiani body and the fusome mediate mitochondrial inheritance during Drosophila oogenesis

Maternally inherited mitochondria and other cytoplasmic organelles play essential roles supporting the development of early embryos and their germ cells. Using methods that resolve individual organelles, we studied the origin of oocyte and germ plasm-associated mitochondria during Drosophila oogenesis. Mitochondria partition equally on the spindle during germline stem cell and cystocyte divisions. Subsequently, a fraction of cyst mitochondria and Golgi vesicles associates with the fusome, moves through the ring canals, and enters the oocyte in a large mass that resembles the Balbiani bodies of Xenopus, humans and diverse other species. Some mRNAs, including oskar RNA, specifically associate with the oocyte fusome and a region of the Balbiani body prior to becoming localized. Balbiani body development requires an intact fusome and microtubule cytoskeleton as it is blocked by mutations in hu-li tai shao, while egalitarian mutant follicles accumulate a large mitochondrial aggregate in all 16 cyst cells. Initially, the Balbiani body supplies virtually all the mitochondria of the oocyte, including those used to form germ plasm, because the oocyte ring canals specifically block inward mitochondrial transport until the time of nurse cell dumping. Our findings reveal new similarities between oogenesis in Drosophila and vertebrates, and support our hypothesis that developing oocytes contain specific mechanisms to ensure that germ plasm is endowed with highly functional organelles.     

Oogenesis in the leech Glossiphonia heteroclita (Annelida, Hirudinea, Glossiphonidae). I. Ovary structure and previtellogenic growth of oocytes

Glossiphonia heteroclita has paired ovaries whose shape and dimensions change as oogenesis proceeds: during early previtellogenesis they are small and club-shaped, whereas during vitellogenesis they broaden and elongate considerably. During early oogenesis (previtellogenesis), each ovary is composed of an outer envelope (ovisac) that surrounds the ovary cavity and is filled with hemocoelomic fluid, in which a single and very convoluted ovary cord is bathed. The ovary cord consists of germline cells, including nurse cells and young oocytes surrounded by a layer of elongated follicle cells. Additionally, follicle cells with long cytoplasmic projections occur inside the ovary cord, where they separate germ cells from each other. The ovary cord contains thousands of nurse cells. Each nurse cell has one intercellular bridge, connecting it to a central anucleate cytoplasmic mass, the cytophore (rachis); it in turn is connected by one intercellular bridge with each growing oocyte. Numerous mitochondria, RER cisternae, ribosomes, and Golgi complexes are transported from the nurse cells, via the intercellular bridge and cytophore, to the growing oocytes. Oogenesis in G. heteroclita is synchronous with all oocytes in the ovary in the same stage of oogenesis. The youngest observed oocytes are slightly larger than nurse cells, and usually occupy the periphery of the ovary cord. As previtellogenesis proceeds, the oocytes gather a vast amount of cell organelles and become more voluminous. As a result, in late previtellogenesis the oocytes gradually protrude into the ovary cavity. Simultaneously with oocyte growth, the follicle cells differentiate into two subpopulations. The morphology of the follicle cells surrounding the nurse cells and penetrating the ovary cord does not change, whereas those enveloping the growing oocytes become more voluminous. Their plasma membrane invaginates deeply, forming numerous broad vesicles that eventually seem to form channels or conducts through which the hemocoelomic fluid can easily access the growing oocytes.     

Accumulation and Spatial Distribution of Poly(A)+RNA in Oocytes and Early Embryos of Drosophila melanogaster

We describe the accumulation and distribution of poly (A)⁺RNA during oogenesis and early embryogenesis as revealed by in situ hybridization with a radio-labeled poly (U) probe. The amount of poly (A)⁺RNA in nurse cell cytoplasm continuously increased untill mid-vitellogenic stage (st. 10), then decreased with the rapid increase of poly (A)⁺RNA in the oocyte (st. 11). The localization of poly (A)⁺RNA at stage 10 was in the anterior region of the oocyte, where it is connected by cytoplasmic bridge to the nurse cells. These observations indicate that most of the poly (A)⁺RNA synthesized in the nurse cells is transferred to the oocyte through the cytoplasmic bridges at stage 10–11. During the remainder of oogenesis (st. 11–14) and during preblastodermal embryogenesis, poly (A)⁺RNA was evenly distributed over the cytoplasm of oocytes and embryos. At blastoderm stage, poly(A)⁺RNA became concentrated in the peripheral region of embryos. Though the somatic nuclei of the blastoderm contained a detectable amount of poly (A)⁺ RNA, the pole cell nuclei did not. The cytoplasmic RNA visualised by acridine orange staining and the poly (A)⁺RNA detected by hybridization with [³H]poly (U) exhibited identical distributions during oogenesis and early embryogenesis. These observations provide a basis to assess the unique distributions of specific RNA sequences involved in early development.     

黄胫小车蝗卵子发生及卵母细胞凋亡的显微观察

对黄胫小车蝗(Oedaleus infernalis)卵子发生过程和卵母细胞凋亡进行显微观察。结果表明,黄胫小车蝗卵子发生可明显分为3个时期10个阶段,即卵黄发生前期、卵黄发生期和卵壳形成期。第1阶段,卵母细胞位于卵原区,经历减数第一次分裂;第2阶段,卵母细胞核内染色体解体成网状,滤泡细胞稀疏地排列在卵母细胞周围;第3阶段,滤泡细胞扁平状,在卵母细胞周围排成一层;第4阶段,滤泡细胞呈立方形排在卵母细胞周围;第5阶段,滤泡细胞呈长柱形排在卵母细胞周围,滤泡细胞之间、滤泡细胞与卵母细胞之间出现空隙;第6阶段,卵母细胞边缘开始出现卵黄颗粒;第7阶段,卵母细胞中沉积大量卵黄,胚泡破裂;第8阶段,滤泡细胞分泌卵黄膜包围卵黄物质;第9阶段,滤泡细胞分泌卵壳;第10阶段,卵壳分泌结束,卵子发育成熟。卵母细胞发育过程中的凋亡发生在卵黄发生前期,主要表现为滤泡细胞向卵母细胞内折叠,胞质呈团块状等特征。     

Variations in mitochondrial size and ultrastructure during germ cell development

Summary Size variations and ultrastructural changes in mitochondria of developing germ cells of the female hamster were analyzed. Mitochondria in oogonia of foetus and newborn were elongate with transverse cristae. During pre-dictyate meiotic prophase they became small, rounded, and electron-dense with pleomorphic cristae. These changes were largely reversed when dictyate was reached. Maximum mitochondrial size and complexity of cristae were reached just at the beginning of the phase of rapid oocyte growth, and thereafter declined. As mitochondrial size and number of cristae decreased in the rapidly enlarging oocyte, the ratio of length to width increased, as did electron density of the matrix, until the formation of an antrum within the follicle. After antrum formation, the mitochondria again became more rounded and cristae were seldom seen. An attempt is made to correlate changes of mitochondrial morphology with other events occurring during oogenesis.The author wishes to thank the Department of Anatomy, University of Dundee, for financial support and for the use of the AEI EM 801 electron microscope     

Vasa protein is localized in the germ cells and in the oocyte-associated pyriform follicle cells during early oogenesis in the lizard <Emphasis Type="Italic">Podarcis sicula</Emphasis>

The vasa gene, first identified in Drosophila, is a key determinant for germline formation in eukaryotes. Homologs of vasa have been identified and linked to germline development, in many invertebrates and vertebrates. Here, we analyze the distribution of Vasa in early germ cells (oogonia and oocytes) and previtellogenic ovarian follicles of the lizard Podarcis sicula. During most of its previtellogenic growth, the oocyte in this lizard species is structurally and functionally integrated through intercellular bridges with special follicle cells called pyriform cells. The pyriform cells function similarly to Drosophila nurse cells, but are somatic in origin. In the oogenesis of P. sicula, Vasa is initially highly detected in the oogonia, but its levels decrease in early stage oocytes before the onset of pyriform cell differentiation. In the later stages of oogenesis, the high level of Vasa is related with the nurse function of the pyriform follicle cells. These observations suggest that cells of somatic origin are engaged in the synthesis of Vasa in the oogenesis of this lizard.     

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。     

The cytology of the vitellogenic stages of oogenesis in Drosophila melanogaster. I. General staging characteristics

The cytology of the vitellogenic stages in the development of the oocyte of Drosophila melanogaster has been studied using whole mounts and sections of plastic-embedded ovaries and single egg chambers for light microscopy and cytochemistry. The migrations, changes in morphology, and synthetic products of the follicle cells are described as a function of developmental stage. The follicle cells synthesize the egg coverings, the vitelline and chorionic membranes, and elaborate the micropyle and dorsal chorionic appendages. The changing structure of the nurse cell nucleus and changes in organelle composition of its cytoplasm are described. The nurse cells synthesize ribosomes, lipid droplets, and mitochondria. These components pass through the ring canal system into the oocyte, which increases in volume some 200,000 times during its 78 hours of development.     

Oogenesis in Hydra: nurse cells transfer cytoplasm directly to the growing oocyte

Oogenesis in Hydra occurs in so-called egg patches containing several thousand germ cells. Only one oocyte is formed per egg patch; the remaining germ cells differentiate as nurse cells. Whether and how nurse cells contribute cytoplasm to the developing oocyte has been unclear. We have used tissue maceration to characterize the differentiation of oocytes and nurse cells in developing egg patches. We show that nurse cells decrease in size at the same time that developing oocytes increase dramatically in volume. Nurse cells are also tightly attached to oocytes at this stage and confocal images of egg patches stained with the fluorescent membrane dye FM 4-64 clearly show large gaps (10 microm) in the cell membranes separating nurse cells from the developing oocyte. We conclude that nurse cells directly transfer cytoplasm to the developing oocyte. Following this transfer of cytoplasm, nurse cells undergo apoptosis and are phagocytosed by the oocyte. These results demonstrate that basic mechanisms of alimentary oogenesis typical of Caenorhabditis and Drosophila are already present in the early metazoan Hydra.     

Gap junctions in ovarian follicles of Drosophila melanogaster: inhibition and promotion of dye-coupling between oocyte and follicle cells

The analysis of chimeras has shown that communication between germ-line and soma cells plays an important role during Drosophila oogenesis. We have therefore investigated the intercellular exchange of the fluorescent tracer molecule, Lucifer yellow, pressure-injected into the oocyte of vitellogenic follicles of Drosophila. The dye reached the nurse cells via cytoplasmic bridges and entered, via gap junctions, the somatic follicle cells covering the oocyte. The percentage of follicles showing dye-coupling between oocyte and follicle cells was found to increase with the developmental stage up to stage 11, but depended also on the status of oogenesis, i.e., the stage-spectrum, in the respective ovary. During late stage 10B and stage 11, dye-coupling was restricted to the follicle cells covering the anterior pole of the oocyte. No dye-coupling was observed from stage 12 onwards. During prolonged incubation in vitro, the dye was found to move from the follicle cells back into the oocyte; this process was suppressable with dinitrophenol. Dyecoupling was inhibited when prolonged in vitro incubation preceded the dye-injection. Moreover, dye-coupling was inhibited with acidic pH, low [K⁺], high intracellular [Ca²⁺], octanol, dinitrophenol, and NaN₃, but not with retinoic acid, basic pH, or high extracellular [Ca²⁺]. Dyecoupling was stimulated with a juvenile hormone analogue and with 20-hydroxyecdysone. Thus, gap junctions between oocyte and follicle cells may play an important role in intercellular communication during oogenesis. We discuss the significance of our findings with regard to the electrophysiological properties of the follicles, and to the coordinated activities of the different cell types during follicle development and during the establishment of polarity in the follicle.     

Aberrant oogenesis in the patterning mutant dicephalic of Drosophila melanogaster: time-lapse recordings and volumetry in vitro

Summary Drosophila females homozygous for the mutation dicephalic occasionally produce ovarian follicles with a nurse-cell cluster on each oocyte pole (dic follicles). Most dic follicles contain 15 nurse cells as in the normal follicle, but the total nurse-cell volume is larger in dic follicles; this is in keeping with the increase in DNA content recently described. However, the relative increase in oocyte volume during nurse-cell regression (from stage 10B onward) is not significantly larger in dic than in normal follicles. Time-lapse recordings in vitro show that, as a rule, both nurse cell clusters in a dic follicle export cytoplasm to the oocyte but nurse-cell regression remains incomplete at both poles and the persisting remnants of the nurse cells cause anomalies in chorion shape. The kinematics of cytoplasmic transfer are less aberrant at that oocyte pole which harbours the germinal vesicle. Possible links are discussed between these anomalies of oogenesis and the double-anterior embryonic patterns observed in the majority of developing dic eggs.     

Site and timing of synthesis of tubulin and other proteins during oogenesis in Drosophila melanogaster

Protein synthetic patterns during oogenesis in Drosophila melanogaster were examined; in particular the site, time, and rate of tubulin synthesis and accumulation during oogenesis were determined. Ovarian proteins were labeled with [³⁵S]methionine in vivo or in organ culure in vitro, and the proteins synthesized in egg chambers of specific developmental stages displayed by two-dimensional gel electrophoresis. A dissection technique was devised to examine proteins synthesized in each of the three cell types present in stage 10B egg chambers. The majority of proteins which were resolved by two-dimensional gel electrophoresis, including tubulin and actin, were synthesized throughout oogenesis and, at least to some extent, in each of the stage 10B cell types. Protein synthesis specific to developmental stage and/or cell type was also observed; for example, two nonchorion proteins were synthesized only in follicle cells and primarily at stage 10. A sensitive and specific radioimmune assay was developed in order to quantitate tubulin accumulation. Synthesis of several α-tubulin subunits and one β-tubulin subunit was observed. The tubulin content per egg chamber increased from 3 ng in stage 9 to 17 ng in stage 14, a period of about 13 hr. An accumulation rate of 1 ng/hr suggests that tubulin mRNA can account for about 4% of the total, nonmitochondrial, poly(A)⁺ RNA of the egg. Analysis of separated cell types at stage 10B revealed that both the follicle and nurse cells synthesize and accumulate appreciable amounts of tubulin. The stage 10B oocyte contains relatively little tubulin but actively synthesizes it. These two complementary analyses demonstrate that the tubulin present in the egg is synthesized within the oocyte-nurse cell syncytium, first in the nurse cells and later in the oocyte.