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1.
通常认为是保护组织的药壁表皮和与花粉囊开裂有关的药室内壁细胞,在单核花粉粒到花粉粒成熟前夕一直保持着活跃的生命活动状态。细胞内具丰富活力旺盛的细胞器,尤其是粗面内质网和囊泡发达的高尔基体以及胞间连丝,细胞核,核仁中的ATP酶活性和线粒体内嵴的细胞色素酶活性达到最强,在二细胞后期,药壁表皮细胞内出现球型颗粒积累,且随着花粉粒的发育逐渐增多,以至当花粉粒被淀粉粒充满时,该颗粒剧增,相当一部分药壁表皮细胞被球型颗粒充满,这时药隔薄壁细胞内也有大量的相同颗粒积累,分析认为药壁表皮细胞内的球型颗粒是来自药隔维管细胞营养物质的积累,药壁表皮和药室内壁细胞旺盛的代谢活性可能与绒毡层解体和花粉粒对营养物质的需求相关。从四分体到单核花粉粒时期,小孢子的发育主要以细胞质的繁殖和体积的增大为主,细胞器数量增加不明显,线粒不发达的内嵴上没有细胞色素氧化酶活性,细胞核和核仁中有ATP酶活性。第一次有丝分裂完成后,花粉粒内壁开始发生,内壁的形成需要能量与质膜参与,成熟的内壁中具径向的,膜性结构的管状通道,在管状通道和外壁的微通道中有显著的ATP酶活性,成熟花粉粒萌发孔区的ATP酶活性更显著。二细胞时期,花粉粒细胞质活性发生较大的变化。各种细胞器成倍增长,功能明显增强,能量出现自给,代谢达到高潮,线粒体内嵴变得发达,内嵴上出现细胞色素氧化酶活性且逐渐增强,成熟的花粉粒被淀粉粒和内嵴发达具显著细胞色素氧化酶活性的线粒体充满。  相似文献   

2.
紫花补血草的大小孢子发生及雌雄配子体发育   总被引:1,自引:0,他引:1  
利用常规石蜡制片法研究了紫花补血草的大小孢子发生及雌雄配子体的发育过程.结果表明:(1)花药壁由表皮、药室内壁、2层中层和绒毡层共5层细胞构成.花药壁发育类型为基本型.表皮细胞内贮藏单宁类物质.药室内壁有纤维性加厚.绒毡层为分泌型绒毡层,成熟绒毡层细胞含2核.(2)小孢子母细胞减数分裂过程中胞质分裂为同时型.小孢子四分体四面体型排列.(3)成熟花粉粒为3.细胞型.(4)胚囊发育类型为贝母型.(5)卵细胞的细胞核位置较为特殊,不是靠近合点端,而是靠近珠孔端.(6)八核胚囊在分化为成熟胚囊时,卵器的细胞常退化.(7)存在过度发育的胚囊.(8)具双胚囊现象.  相似文献   

3.
本文利用透射电镜、半薄切片等技术,对银杏小孢子囊壁的发育进行了观察和研究。银杏小孢子囊壁分为表皮、内壁、中层和绒毡层。(1)对小孢子囊壁的表皮、内壁和中层细胞的观察表明,小孢子母细胞时期,这些细胞均处于活跃的代谢和合成阶段,含有大量的细胞器如线粒体、高尔基体、内质网和核糖体等;减数分裂时期细胞的细胞质浓度逐渐降低,细胞内分布有大液泡,其中表皮细胞的液泡膜上形成大量贮藏蛋白,内壁细胞的细胞壁逐渐皱缩,中层细胞纵向拉伸;有丝分裂时期,细胞的细胞质逐渐降解,内壁细胞切向壁和径向壁均出现大量乳突状纤维加厚,中层细胞解体,最后仅剩残余。(2)绒毡层细胞属于分泌型,在小孢子母细胞时期细胞内的细胞器丰富,其中质体在减数分裂过程中达到高峰;游离小孢子时期,粗糙内质网达到最大,绒毡层开始形成乌氏体,最终结合到花粉外壁,参与花粉外壁的形成;有丝分裂后期,绒毡层通过自溶的形式解体。以上结果显示,银杏的小孢子囊壁在为花粉发育提供营养和保护作用方面起着重要作用。  相似文献   

4.
小麦花粉萌发孔与雄性不育关系初探   总被引:4,自引:0,他引:4  
本文运用扫描电镜和ATP酶细胞化学标记技术,对同核异质和异质同核T型、V型、K型雄性不育系花粉粒萌发孔内、外结构特征以及ATP酶活性分布变化进行了研究。结果不仅观察到花粉粒萌发孔孔盖的突出程度与花粉粒败育的早晚成正相关,而且还观察到萌发孔孔盖与孔环的接触程度与不育系的恢复度有关。进一步分析研究认为萌发孔孔盖突出的不同程度是由萌发孔区Zwischenkorper层与内壁的缺乏和结构异常造成的,微丝的解聚在Zwischenkorper层和内壁两者结构破坏过程中起着重要的作用。  相似文献   

5.
剑尾鱼肝脏结构的光镜和透射电镜观察   总被引:4,自引:0,他引:4  
应用光学显微镜和透射电镜对剑尾鱼(Xiphophorus helleri)肝脏的组织结构和超微结构进行了观察。结果表明,剑尾鱼肝细胞存在双态现象,根据其胞质内的电子密度不同可以区分为D细胞和L细胞2种类型。剑尾鱼肝细胞具单核,核仁显著;胞质内含有粗面内质网、线粒体、糖原颗粒和脂滴等细胞器和内含物。胆小管由相邻肝细胞质膜凹陷围成,而肝血窦则由内皮细胞的胞质、成纤维细胞、贮脂细胞和枯氏细胞参与构成。并讨论了硬骨鱼类肝脏的一般组织结构和超微结构特点。  相似文献   

6.
本文用电镜观察了三例何杰金氏病淋巴结,典型R-S细胞形态大、镜影核和大核仁。核仁结构以颗粒型为多,内有大小不等的浅亮间隙,这可能表明了R-S细胞内RNA代谢紊乱。R-S细胞核仁边集现象少见,似乎不利于核仁内物质转移到胞浆中去。有关R-S细胞起源本文支持来自单核——巨噬细胞系统。R-S细胞和淋巴细胞之间所形成的狭窄间隙,少数连接处局部胞膜有破损,它揭示了体内淋巴细胞对肿瘤免疫反应的表现。  相似文献   

7.
一般生物体的细胞溶质的游离钙离子水平约为10~(-6)—10~(-8)M,而细胞外可达10~(-3)M。细胞溶质内的游离钙离子浓度对钙调蛋白的活性有调节作用,要维持细胞溶质的低钙离子浓度需要通过Ca~#—ATP酶从细胞溶质主动将钙离子泵至膜外或液泡。液泡大量积累钙离子并形成不溶性的钙盐,叶绿体与线粒体都是细胞质中的钙库。我们以玉米根细胞作材料,用改良焦锑酸钾沉淀法定位钙离子,观察植物细胞内液泡、叶绿体和线粒体中积累的钙转移的途径。在幼嫩的细胞中,含有大量钙的贮存器及老化的细胞器和液泡膜融合后,钙进入液泡(图1)。另外一  相似文献   

8.
三裂叶豚草(Ambrosia trifida L.)是世界公认的恶性杂草。它的危害性主要在于其花粉对人体产生严重的致敏作用。本文利用扫描电子显微镜对三裂叶豚草的花粉外部形态进行了观察,并利用石蜡切片和光学显微镜对其雄配子体发育进行了系统研究。结果表明:花粉粒球形,外壁呈刺状纹饰,三孔沟。花药壁由4层细胞组成,分别为表皮、药室内壁、中层和绒毡层。绒毡层发育类型为变形绒毡层。小孢子母细胞胞质分裂为连续型,四分体主要为四面体形。成熟花粉粒为3-细胞型。  相似文献   

9.
肉苁蓉雌雄配子体发育的研究   总被引:1,自引:1,他引:0  
肉苁蓉(Cistanche deserticola Y.C.Ma)是一种沙生根寄生濒危药用植物.采用石蜡切片法,利用光镜观察,对内苁蓉雌雄配子体发育进行了系统研究.结果表明:花药壁由5层细胞组成,分别为表皮、药室内壁、中层(2层)和绒毡层,绒毡层细胞起源具异型性,发育类型为腺质型.小孢子母细胞胞质分裂为同时型,四分体为四面体型,成熟花粉粒为2-细胞型,部分败育.大孢子由单个孢原细胞直接发育为大孢子母细胞,大孢子母细胞减数分裂形成线状四分体,珠孔端3个大孢子最后退化,且退化顺序不一,大部分胚囊中的大孢子从合点端第2个开始退化,合点端大孢子为功能大孢子并发育为单核胚囊,胚囊发育属蓼型.研究结果为内苁蓉资源的保护提供细胞学依据.  相似文献   

10.
快速分离大白鼠肝细胞,用H~3尿嘧啶处理,再孵育于无放射性尿嘧啶和DRB药内,用电镜放射自显影技术测定核放射性,在这些条件下显示染色质间颗粒被标记,并用低剂量Actinomycin D颗粒处理细胞,这些观察指出在DRB处理细胞内,染色质间颗粒是核仁RNA聚集或运输部位。染色质间颗粒(IG)存在于大多数细胞核的核质内,如形态学上已确定的结构,平均直径为200—250A,由细的原纤维联接成不同大小IG丛,用Bcrnhard选择性RNP染色法,IG显示强染色,本实验用DBR处理分离肝细胞后,出现了特殊的IG丛,这些IG丛含有核仁起源的RNA,亦证明了IG是核仁RNA的聚集或运输部位,但对IG  相似文献   

11.
DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.  相似文献   

12.
From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.  相似文献   

13.
The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.  相似文献   

14.
The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.  相似文献   

15.
Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.  相似文献   

16.
This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel's.  相似文献   

17.
A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.  相似文献   

18.
A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.  相似文献   

19.
Call for Papers     
正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks  相似文献   

20.
正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first  相似文献   

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