Comparative studies on leaf epidermal micromorphology and mesophyll structure of Elaeagnus angustifolia L. in two different regions of desert habitat

In order to obtain qualitative and quantitative characteristics of leaf epidermal micromorphology and mesophyll structure to evaluate the responses of Elaeagnus angustifolia L. to different environment...     

The Ultrastructure and Origin of Upper Sinian Cherts on the Southeast Continental Margin of the Yangtze Platform1

Abstract Through microscopic and SEM observations and X-ray diffraction and energy spectrum analyses, the oldest sponge spicules and radiolarians have been found in bedded cherts and it is proposed that microbial activity of algae and bacteria played an important role in silica precipitation. The microbial activity resulted in the formation of a series of single crystals and crystal aggregates with peculiar shapes. Biogenic single crystals usually occur in spherical, rod, platy, colloidal and granular forms. The most common aggregates are framboidal aggregates composed of dense spherical quartz crystals, which are considered to be of typical bacterial origin. Other aggregates, such as favositic, double-spherical, chain -spherical and coccoid ones, are considered to be probably the result of silicification of algal cells and mainly of primary sedimentary origin. This paper also discusses the ultrastructural features and diagnostic indications of jasper rocks formed in a submarine hydrothermal environment and cherts formed by replacement and diagenetic recrystallisation.     

Cuticle ultrastructure of Pseudofrenelopsis gansuensis: Further taxonomical implications for Cheirolepidiaceae

A study of the cheirolepidiaceous conifer Pseudofrenelopsis gansuensis from the Lower Cretaceous of Wangqing Jilin Province in China was conducted in detail using scanning and transmission electron microscopy techniques. In total, nine ultrastructural features were recognized for the cuticle of this fossil plant, which are helpful in the distinguishing between cuticles of ordinary epidermal cells, subsidiary cells, guard cells and hypodermal cells of the stomatal apparatus. A three dimensional reconstruction of the cuticle ultrastructure was obtained. Pseudofrenelopsis gansuensis is the second species of this genus for which the cuticle ultrastructure has been statistically examined with 30 measurements and estimated confidence interval values. The close comparison of the cuticle ultrastructure characters, including statistical data, among Cheirolepidiaceae and other fossil conifers provides potential evidence of the taxonomic significance of this genus: ten characters are potentially valuable for specific separation, eleven parameters for generic separation and three parameters seem also to be useful for Family determination. The differences in the chemical composition according to preliminary statistical element analyses of the cuticles based on three ratios in two species of Pseudofrenelopsis, P. dalatzensis and P. gansuensis, should also be examined in future studies.     

Eco-physiological mechanisms of Caragana korshinskii Kom. adaptation to extreme drought stress: Leaf abscission and maintaining stem chloroplast integrity

In order to study the eco-physiological mechanisms of C. korshinskii adaptation to extreme drought stress, we investigated the variations of water content in soil, leaves, and stems, the chlorophyll a and b and the carotenoid content in leaves and stems, as well as changes of chloroplast ultrastructure in 2-year-old C. korshinskii specimens during a progressive soil drought process (by ceasing watering until all leaves were shed) and a subsequent rehydration process. During the dehydration process, the chlorophyll a and b and carotenoid contents in the leaves decreased, as did the carotenoid content in the stems. During the 4-day rehydration process, the chlorophyll a and b and carotenoid contents in the leaves and stems increased and gradually returned to normal levels. During ongoing drought stress, chloroplasts in the leaves broke away from cell walls and appeared in the center of cells. Under severe drought stress, the mesophyll ultrastructure and chloroplast configuration in leaves were irreversibly disturbed, as manifested by the inner and outer membranes being destroyed; the thylakoid system disintegrated, the starch grain disappeared, and parts of cell tissue were dismantled into debris. However, the mesophyll ultrastructure and chloroplast configuration in the stems remained complete. This indicates that C. korshinskii utilizes leaf abscission to reduce the surface area to avoid damage from extreme drought stress, and maintains chloroplast integrity and a considerable amount of chlorophyll to enable a rapid recovery of photosynthesis under the rehydration process.     

中国对虾眼柄神经分泌结构的超微结构研究

利用电镜技术并结合半薄切片对中国对虾眼柄神经分泌细胞和窦腺进行观察，依据神经分泌细胞的直径以及细胞核、细胞器、分泌颗粒的特征将其分成6种类型，依据神经分泌颗粒的直径、形态、密度特征将窦腺中的神经分泌颗粒分成6种类型。     

岩虫消化管组织学、组织化学和超微结构的初步研究

运用光学显微镜、透射电镜和组织化学方法初步研究了岩虫（Marphysa sanguinea）消化管的组织结构和消化酶的分布。结果显示：岩虫消化管呈长直管状,可分为口咽腔、食道、肠和后肠。组织化学研究表明食道粘膜层固有层有分泌酸性粘多糖、中性粘多糖和混合粘多糖3种粘液细胞;肠及消化盲囊的上皮细胞游离端及顶部胞质均检测到碱性磷酸酶、酸性磷酸酶和酯酶的活性。透射电镜显示食道粘膜固有层的粘液细胞可分为含低电子密度颗粒、高电子密度颗粒和电子透明颗粒3种。肠和消化盲囊绒毛发达,上皮细胞表面具丰富微绒毛,游离端细胞质中可见酶原颗粒、吞饮小泡、丰富的粗面内质网及溶酶体。肠纤毛沟由纤毛柱状上皮细胞组成,带环状横纹的纤毛小根插入细胞内部,纤毛小根之间散布着丰富的线粒体、溶酶体等结构。     

刺巨藤壶精子的发生及其超微结构

采用扫描和透射电镜技术, 观察刺巨藤壶(Megabalanus volcano)精子发生和精子的超微结构特征。结果显示, 刺巨藤壶精子发生经历精原细胞、初级精母细胞、次级精母细胞、精细胞和精子等5个阶段。在精子形成期间, 圆形或椭圆形的细胞核在微管的作用下沿轴丝延长并在胞质内弯曲, 核和轴丝随着精细胞的纵向伸长而延长, 细胞核最终成为线状; 斑块状的染色质逐渐解体, 呈细小颗粒状和粗颗粒状, 最后浓缩成高密度的均质物; 高尔基体分泌的囊泡不断融合, 形成大小不一的附属小滴前体, 最后融合并延伸成一个纺锤形的附属小滴; 许多小的线粒体不断融合成一个细长的线粒体, 移至核的后端。精子为前部带有附属小滴的长线状, 全长约58.39μm, 可分为顶体、颈部、中段和尾部四部分。长锥形的顶体位于精子最前端, 其后为基体; 颈部由基体产生的“9+2”型轴丝和与之并行的线状核组成; 顶体和颈部两者长共约6.65μm。中部长约42.95μm, 纺锤形的附属小滴(长约9.33μm, 最宽处约2.13μm)紧靠核和轴丝, 其后为颗粒状糖原及一个细长的线粒体; 尾部长约8.79μm, 只有轴丝贯穿。     

The Gastric Shield and the Underlying Epithelium of Chlamys Farreri:Morphological, Histological and Histochemical Characterizations

Ｂｉｖａｌｖｅｓｈａｖｅｔｒａｎｓｌｕｃｅｎｔｔｈｉｎｍｅｍｂｒａｎｅｓ—ｔｈｅｇａｓｔｒｉｃｓｈｉｅｌｄｃｏｖｅｒｓｏｎｔｈｅｌｅｆｔｏｆｔｈｅｐｏｓｔｅｒｉｏｒｓｔｏｍａｃｈｗａｌｌｓ;ｔｈｅｈｅａｄｏｆｔｈｅｃｒｙｓｔａｌｌｉｎｅｓｔｙｌｅｈｏｕｓｅｄｉｎｔｈｅｓｔｙｌｅ ｓａｃｉｓｒｏｔａｔｅｄｆｏｒｗａｒｄｉｎｔｏｔｈｅｓｔｏｍａｃｈｔｏｉｍｐｉｎｇｅｔｈｅｆｏｏｄｏｎｔｈｅｇａｓｔｒｉｃｓｈｉｅｌｄ (ＺｈａｎｇａｎｄＴａｉ,1 961 ) .Ｉｔｗａｓｒｅｐｏｒｔｅｄｔｈａｔｔｈｅｇａｓｔｒｉｃ…     

Ultrastructure of Single Cells, Callus-like and Monosore-like Cells in Porphyra yezoensis Ueda on Semi solid Culture Medium

It had been demonstrated that individual cells or protoplasts isolated from Porphyra thallus by enzyme could develop into normal leafy thalli in the same way as monospores, and that isolated cells develop in different way in liquid and on semi solid media. The authors observed the ultrastructure of isolated vegetative cells cultured on semi solid media and compared them with those of monospores and isolated cells cultured in liquid media. The results showed that subcellular structures were quite different among cells in different conditions. In their development, isolated cells on semi solid media did not show the characteristic subcellular feature of monospore formation, such as production of fibrous vesicles. Callus like cells formed on semi solid media underwent a distinctive modification in cellular organization. They developed characteristic cell inclusions and a special 2 layer cell covering. Golgi bodies, ER, starch grains, mitochondria. Vacuoles were not commonly found in them.