文昌鱼卵子发生中成熟分裂时卵母细胞的超微结构研究

首次观察文昌鱼卵发生进入和一次成熟分裂前期联合会丝复合粗线期,双线期和网状期卵原细胞及卵母细胞生发泡及胞质的超微结构特点,在生发泡内同源染色体配对,联会丝复合体中央出现重组节。不同发育类型的核样体及其相关线粒体是这一时期卵母细胞胞质的主要特征     

卤虫的卵子发生研究

了解卤虫的卵子发生过程对于研究甲壳动物配子发生,胚胎发生的形成学起着极为重要的作用。本文联系其他物种的卵子发生现象针对卤虫卵子发生过程中的重要现象作了较详细的综述,包括卤虫卵黄发生早期的联会复合体的形态,卵母--营养细胞复合体的形成,卵黄发生期的卵黄形成以及营养细胞和体细胞的变化。而且发现在蜕皮类激素与卵黄发生之间存在着一些联系。另外,本文对卤虫雌性生殖器官以及显微结构也作了简要的介绍。     

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。     

剑尾鱼卵子发生的的组织学观察

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,剑尾鱼卵巢中的卵母细胞的发育是不同步的。     

鲻鱼甲状腺免疫组织化学与超微结构

用组织学、免疫组织化学和电镜技术对鲻鱼甲状腺的分布与形态结构进行研究。结果表明，鲻鱼甲状腺滤泡分散地分布在第1对至第3对鲻弓的入鳃动脉之间；构成同一滤泡的单层上皮细胞呈扁平形和立方形两种形态，反映出同一滤泡中上皮细胞生理活动的不同步，且发现不同发育时期的鲻鱼这两种形态细胞的比例有显著差异。用特异性甲状腺球蛋白(TG)抗体对甲状腺滤泡的免疫染色反应显示，阳性物质分布在滤泡上皮细胞的脑膜及围绕滤泡腔的周边与中央胶质，幼年与成年鲻鱼甲状腺滤泡的免疫阳性反应部位有所不同。两种不同活动状态的细胞，扁平形细胞和立方形细胞，在核与胞质的超微结构上有显著不同。扁平形细胞的核为扁平形或椭圆形，核内常染色质十分丰富，核膜光滑，核周腔和核孔没有扩张，胞质中各种细胞器发育较差；立方形细胞的核膜高度凹陷，将核分为2叶至3叶，核周腔和核孔扩张，胞质中各种细胞器发育良好，出现长棒形和哑铃形线粒体，且数量明显多于扁平形细胞，多层粗面内质网呈板层状排列，还有发育好的高尔基复合体。另外，我们还观察到一种介于扁平形细胞和立方形细胞之间的中间型细胞，其胞质和核的发育明显好于扁平形细胞，但比立方形细胞差。上述结果可为了解鲻鱼甲状腺滤泡细胞分泌活动的机制提供基础资料[动物学报49(2)：230—237，2003]。     

猕猴精母细胞联会复合体的银染色观察

作者以银染的雄性猕猴减数分裂标本,研究联会复合体的形成和行为,特别是性泡内X、Y染色体有规律的变化。指出常染色体联会复合体的形成开始于偶线期,成熟于粗线期,开始消失于弥散期。在粗线期可见20条清晰的常染色体联会复合体,其中1条带有呈深黑色的核仁组织者。X、Y染色体同源区段的配对,开始于早粗线期。随着粗线期的发展,由侧面配对转为端部配对状。性染色体配对的解体也比常染色体联会复合体晚,在弥散期仍清晰可见。在整个前期,X、Y的着色也比常染体联会复合体深。在一些细胞中,X染色体显示一种特殊的“发夹状”结构。这是在性染色体进化过程中X染色体由于易位得到的重复片段在粗线期同源配对的一种细胞学表现。     

拟目乌贼卵子发生与卵巢发育

为了丰富拟目乌贼(Sepia lycidas)生物学资料, 为人工育苗与养殖提供理论依据, 采用解剖学和组织学的方法, 对水泥池养殖条件下拟目乌贼卵子发生和卵巢发育进行了研究。结果表明: 经过6个月水泥池养殖, 平均体重为256.34 g, 最大体重达到457.08 g, 个别发育成熟, 绝大部分未达性成熟。卵子发生不同步, 根据细胞形态、细胞大小、滤泡细胞形态和卵黄形成情况可分为卵原细胞阶段(卵原细胞期)、原生质生长阶段(无滤泡期、单层滤泡期和双层滤泡期)、间质生长阶段(滤泡内折早期、滤泡内折中期和滤泡内折晚期)和营养质生长阶段(卵黄发生早期、卵黄发生晚期和成熟期), 共4个阶段10个时期。卵巢发育根据外观形态、性腺指数变化和切面上各期细胞所占的比例, 可分为形成前期、形成期、小生长期、大生长期、成熟前期和成熟期6个时期。拟目乌贼繁殖周期为一年。       

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     

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,核伸出伪足状突出,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。     

标记减数分裂遗传重组的免疫荧光染色方法

联会复合体免疫荧光技术在全基因减数分裂遗传重组研究中具有精确和直观的优势.本研究通过免疫荧光染色方法制备小鼠精母细胞联会复合体,研究其形态组成与遗传重组特征,展示雄性小鼠遗传重组图谱并分析其重组位点(MLH1位点)的分布特征.4只小鼠共145个精母细胞在平均每个细胞的MLH1位点数为23.3±2.4;在常染色体联会复合体中,未发现有3个MLH1位点的联会复合体,具有1个MLH1位点的联会复合体较多,平均为14.2;无XY联会复合体的细胞占所有细胞的4.1%,XY联会复合体上有MLH1位点的细胞占30.2%;联会复合体上有裂缝的细胞占0.7%.通过联会复合体免疫荧光染色可以清晰地分辨出联会复合体(红色)、着丝粒(蓝色)和MLH1位点(绿色),是遗传重组分析的一种强有力工具.     

Histological studies on early oogenesis in barfin flounder (Verasper moseri)

There is much information on oogenesis from the resumption of the first meiotic division to oocyte maturation in many vertebrates; however, there have been very few studies on early oogenesis from oogonial proliferation to the initiation of meiosis. In the present study, we investigated the histological changes during early oogenesis in barfin flounder (Verasper moseri). In fish with a total length (TL) of 50mm (TL 50mm fish), active oogonial proliferation was observed. In TL 60mm fish, oocytes with synaptonemal complexes were observed. Before the initiation of active oogonial proliferation, somatic cells which surrounded a few oogonial germ cells, started to proliferate to form the oogonial cysts that accompanied oogonial proliferation. In TL 70mm fish, however, the cyst structure of the oocyte was gradually broken by the invagination of somatic cells, and finally the oocyte became a single cell surrounded by follicle cells. Upon comparison of nuclear size, DNA-synthesizing germ cells could be divided into two types: small nuclear cells and large nuclear cells. Based on histological observation, we propose that the small nuclear cells were in the mitotic prophase of oogonia and the large nuclear cells were in the meiotic prophase of oocytes, and that the nuclear size increases upon the initiation of meiosis.     

PAR-1 is required for the maintenance of oocyte fate in Drosophila

The PAR-1 kinase is required for the posterior localisation of the germline determinants in C. elegans and Drosophila, and localises to the posterior of the zygote and the oocyte in each case. We show that Drosophila PAR-1 is also required much earlier in oogenesis for the selection of one cell in a germline cyst to become the oocyte. Although the initial steps in oocyte determination are delayed, three markers for oocyte identity, the synaptonemal complex, the centrosomes and Orb protein, still become restricted to one cell in mutant clones. However, the centrosomes and Orb protein fail to translocate from the anterior to the posterior cortex of the presumptive oocyte in region 3 of the germarium, and the cell exits meiosis and becomes a nurse cell. Furthermore, markers for the minus ends of the microtubules also fail to move from the anterior to the posterior of the oocyte in mutant clones. Thus, PAR-1 is required for the maintenance of oocyte identity, and plays a role in microtubule-dependent localisation within the oocyte at two stages of oogenesis. Finally, we show that PAR-1 localises on the fusome, and provides a link between the asymmetry of the fusome and the selection of the oocyte.     

Mago Nashi, Tsunagi/Y14, and Ranshi form a complex that influences oocyte differentiation in Drosophila melanogaster

During Drosophila melanogaster oogenesis, a germline stem cell divides forming a cyst of 16 interconnected cells. One cell enters the oogenic pathway, and the remaining 15 differentiate as nurse cells. Although directed transport and localization of oocyte differentiation factors within the single cell are indispensible for selection, maintenance, and differentiation of the oocyte, the mechanisms regulating these events are poorly understood. Mago Nashi and Tsunagi/Y14, core components of the exon junction complex (a multiprotein complex assembled on spliced RNAs), are essential for restricting oocyte fate to a single cell and for localization of oskar mRNA. Here we provide evidence that Mago Nashi and Tsunagi/Y14 form an oogenic complex with Ranshi, a protein with a zinc finger-associated domain and zinc finger domains. Genetic analyses of ranshi reveal that (1) 16-cell cysts are formed, (2) two cells retain synaptonemal complexes, (3) all cells have endoreplicated DNA (as observed in nurse cells), and (4) oocyte-specific cytoplasmic markers accumulate and persist within a single cell but are not localized within the posterior pole of the presumptive oocyte. Our results indicate that Ranshi interacts with the exon junction complex to localize components essential for oocyte differentiation within the posterior pole of the presumptive oocyte.     

Population biology of parasites of striped mullet, Mugil cephalus L. I. Monogenea

Young-of-the-year (class 0) and yearling (class 1) striped mullet, Mugil cephalus , were collected from Sapelo Island, Georgia from May 1970 to June 1971 to study the development, seasonal abundance and relationship of environmental variables to parasitic populations. The number of species of parasites increased with age of the host. Initial infection appeared to be influenced by closeness of association of mullet age classes, by the period of abundance of a parasite on class I mullet and by the mobility of the infective parasitic stage. Fluctuations in intensity and prevalence of a parasite on class 0 mullet were similar to those of class I mullet after the initial infection. Ancyrocephalus vanbenedenii was first observed on class 0 mullet in March. Intensity was high on both classes in spring and on reproductively active mullet in late autumn. Prevalence on both classes was above 80% except in late summer. Polyclithrum mugilis was not observed on class 0 mullet until August even though intensity and prevalence on class I mullet was highest during early spring. Gyrodactylus mugelus did not occur on class 0 mullet but appeared on class I mullet during late summer. Microcotyle psuedomugilis was observed on class 0 mullet in early summer and Metamicrocolyla maeracantha in October. Both species occurred but at a low intensity on class I mullet.     

Mitochondrial development during Drosophila oogenesis: distribution, density and in situ RNA hybridizations.

The changes in distribution and density of mitochondria and the level of mitochondrial RNA during Drosophila oogenesis were studied simultaneously in the 3 cell types ie follicle cells, nurse cells and oocyte, making up the egg chamber. Up to stage 6, mitochondrial density (mitochondrial and cellular areas ratio) was elevated and increased similarly in both follicle and nurse cells. Thereafter the mitochondrial density of follicle cells continued to increase and that of the nurse cells declined markedly while the nurse cell mitochondria assembled in dense groups and decreased in size. This can be related to a transfer of nurse cell cytoplasm, including mitochondria, to the oocyte. In the oocyte from stage 4 to stage 7 we observed a significant decrease of the mitochondrial density due to the absence of mitochondrial biogenesis. Then the cytoplasm transfer caused mitochondrial density to increase up to the level found in the nurse cells at the end of oogenesis. The mature oocyte contains enough mitochondria to supply 15,000 somatic cells. Our results strongly suggest that the variations in size, distribution and density of mitochondria relate to the particular energetic requirements of the different cell types during the first half of oogenesis. Later they relate to the developmental requirements of the nurse cells and the oocyte, in particular the storage of mitochondria in the oocyte. The level of mitochondrial RNA was studied through in situ hybridization. Throughout oogenesis the follicle and nurse cell RNA evolved similarly. Up to stage 9, there was no change in RNA densities in these cells, suggesting a correlation with the cell volume and/or the nuclear DNA content. Thereafter the cellular RNA concentration declined rapidly. In the oocyte the RNA concentration evolved differently especially from stage 10 to the end, the RNA density being stabilized. This can be related to the injection of nurse cell mitochondria, followed by their assignment to reserve status. Our results suggest that the mt RNA density is under extramitochondrial control mechanisms.     

Ultrastructural observations of the early and late stages of gorgonian coral (Junceella juncea) oocytes

The developmental oogenesis of gorgonian coral was investigated at the histological level. The objective of this study was to examine and improve the understanding of Junceella juncea oogenesis using ultrastructural methods, such as histological sectioning and transmission electron microscopy. At least three types of yolk materials were observed in this study: yolk body, lipid granules and cortical alveoli. Some of the complex yolk materials were encompassed by concentric or arched layers of smooth and rough endoplasmic reticulum and the Golgi complex in early stage oocytes. Different types of vesicles were found in both early and late stage oocytes and some granules could be seen inside the empty vesicles. This may be a possible method for elaborating complex yolk materials. Homogeneous yolks from different types of inclusions were abundant and the autosynthesis of yolk may be a major mechanism in J. juncea oocytes. This is the first report of the ultrastructural observation of oogenesis in gorgonian coral species using transmission electron microscopy. Our study obtained relatively detailed information at the ultrastructural level, and it provides an overview of the oocyte ultrastucture of the gorgonian coral J. juncea.     

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 ].     

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。     

The meiotic prophase in Bombyx mori females analyzed by three-dimensional reconstructions of synaptonemal complexes

Serial sectioning followed by three dimensional reconstruction of lateral components of the synaptonemal complex have been used to follow chromosome pairing during the prophase of the achiasmatic meiotic division in the silkworm, Bombyx mori. During leptotene and early zygotene, the lateral components become attached to the nuclear envelope at a specific region, thus forming a chromosome bouquet. The attachment of lateral components to the nuclear envelope precedes the completion of the components between their attachment points. Synapsis and synaptonemal complex formation start during the period of lateral component organization in the individual nucleus. Telomeric movements on the nuclear envelope occur at two stages of the prophase: the chromosome pairing appears to be initiated by an association of unpaired ends of homologous chromosomes, the nature of this primary attraction and recognition being unknown. Secondly, the paired chromosomes become dispersed in the nucleus by shifting of attachment sites of completed synaptonemal complexes at the end of zygotene. This movement is possibly related to a membrane flow occurring during this stage. Membrane material is synthesized at the region of synaptonemal complex attachment. Later, the excess membrane material is shifted to the opposite pole where it protrudes into the lumen of the nuclei thus forming vacuoles. — Two previously undescribed features of chromosome pairing were revealed. In late zygotene, chromosome pairing and synaptonemal complex formation were frequently observed to be delayed or even prevented over a short distance by interlocking of two bivalents, both being attached to the nuclear envelope. Such interlocking of bivalents was not found in pachytene. Secondly, one nucleus was found in which two homologous chromosomes were totally unpaired while the remaining 27 bivalents were completed or in a progressed state of pairing. The lateral components of the two unpaired chromosomes had the same length and were located several microns apart, thus eliminating the possibility of a permanent association of homologous chromosomes before the onset of meiosis in Bombyx mori females. — During pachytene, one of the 8 cells belonging to the syncytial cell cluster characteristic of oogenesis continues the meiotic prophase whereas the remaining 7 cells, the nurse cells, enter a different developmental sequence, finally resulting in their degeneration. The synaptonemal complex of the oocyte develops into a sausage-like structure after pachytene by a deposition of dense material onto the lateral components, thus filling out most of the central region. The diameter of this modified synaptonemal complex reaches at least 300 nm, as compaired to a pachytene width of approximately 130 nm. Also, the length of synaptonemal complexes increases from 212 at zygotene/pachytene to at least 300 at the modified pachytene stage. In nurse cells, synaptonemal complexes are shed from the bivalents shortly after pachytene simultaneously with a condensation of the chromatin. These free synaptonemal complex fragments associate and form various aggregates, either more or less normal looking polycomplexes or various complex figures formed by reorganized synaptonemal complex subunits. Later stages have not been included in the present investigation.