Scanning Electron Microscopic Studies of Candida albicans

A scanning electron microscopic study of selected morphological stages of Candida albicans is presented. Stages represented are budding yeast cells, mycelial-like forms, chlamydospores, germ tube formation, and an unusual rough cell type.     

Scanning Electron Microscopic Studies on the Organ Development of

The pattern of development of the floral parts of Longan flower was followed using scanning electron microscope. Floral initiation begins with the formation of calyx protrusions around the floral apex. After the calyx protrusions have appeared, the petal primordia at the base of the floral apex start to appear and then followed by the androecium primordia which appear at the periphery of the floral apex. Gynoecium formation begins much later (at about 30 days after floral initiation). In the male flower, androecium develops normally forming anthers and filaments. Anthers also develop in the female flowers but they are smaller and the filaments much shorter. Gynoecium in the female flower is well developed and when mature it produces a long style, a two-prong-stigma and two ovaries. In the male flower the gynoecium is poorly developed the style is short and the stigma seldom splits. Ovaries are also poorly developed in the male flower. In addition to male and female flowers, Longan also forms a number of abnormal flowers with poorly developed androecium and gyn6ecium. Male and female flowers only become apparent at about 40 days after the initiation of flower differentiation. Prior to this it is difficult to know whether a particular developing flower is going ultimately to become a male or female flower. The formation of abnormal flowers also become obvious' at about 40 days after the initiation of flower differentation.     

A Scanning Electron Microscopic Evaluation of Section and Film Mounting for Transmission Electron Microscopy

Mounting of support films and sections for transmission electron microscopy has been examined with the scanning electron microscope. Experiments have been designed to test the adherence of support films to polished and matte surfaces of specimen grids. It is the conclusion of the authors that sections and films should be mounted on the dull or matte surface of Athene-type specimen grids.     

A New Imprinting Material for Scanning Electron Microscopic Studies

A new imprinting material, “Ther-mocool”, has been used for preparing negative replicas of plant as well as metal surfaces for SEM study. The technique has wide application and gives very good results.     

Scanning and Transmission Electron Microscopic Observations on Surface Structures of Three Turbellarian Species

The body surface of Microstomum lineare, Bothriomolus balticus and Archilopsis unipunctata was examined in scanning electron microscope. The threedimensional appearance of adhesive duo-gland organs, receptor cilia, globular bodies and pistil-like projections is described. The adhesive duo-gland papillae of Bothriomolus and Archilopsis appear as bouquetlike structures on either side of the tail as well as on the cilia covered body. In Microstomum the papillae occur as single projections among the ciliary body für. Supplementary TEM investigation revealed crystalline bodies in the cytoplasm of viscid gland cells.     

Scanning Electron Microscopic Studies on the Development of the Organs of Litchi Flower

The pattern of development of the floral parts of litchi (Litchi chinensis Sonn.) flower was followed using scanning electron microscopy. Before making scanning electron microscopic observations, specimens were tannin-osmium impregnated and critical point dried. In the bisexual flower, floral organogenesis starts with the formation of protrusions near the floral apex. The two to three protrusions present at the apical region of the floral apex later expand and fuse to form the ovary. At the upper middle region of the ovary another protrusion develops which later becomes the style and the stigma. When the flower matures the tip of the style not only splits but also becomes twisted. On the upper side of the stigma there are numerous papillate cells. These cells are covered with mucilage when fully mature. The development of the filament and anther begins a little bit earlier than the gynoecium. The first sign of androecium development begins when protrusions start to develop around the floral apex. Each litchi flower possesses 6 to 10 anthers. In addition to forming bisexual flowers, litchi also produces a large number of male and female unisexal flowers. But under the scanning electron microscope it is very difficult to distinguish accurately between male and female flowers, because both flowers invariably give rise to some poorly developed organs of the opposite sex. Thus it seems that all flowers in litchi are potentially bisexual and only at the final stage of development (i.e. about 50 days after floral initiation) sex organs fail to develop properly in some flowers.     

Studies on the effects of vinblastine and colchicine on Trypanosoma gambiense

Vinblastine and colchicine induce the anucleate form of Trypanosoma gambiense. Light microscopic studies indicated that the anucleate form was not always produced as a result of inhibition of nuclear duplication, but was formed as a result of delay or inhibition of separation of the two nuclei after completion of nuclear division. Studies showed that vinblastine and colchicine caused disorder in arrangement of axonemal microtubules of the extracellular flagella and increased formation of both protofilaments and the axoneme composed of protofilaments in trypanosomes. Moreover, treatment with colchicine resulted in disintegration of previously existing pellicular microtubules and formation of cytoplasmic projections that appeared as protrusions from a small part of the surface membrane.     

Transmission and Scanning Electron Microscopic Observations on the Plasmodesmatal Channels Between the Pollen Mother Cells of Lily

The regularity of the presence of plasmodesmata channels in the pollen mother cells of lily was studied by transmission and scanning electron microscopy. A few plasmodesmata channels can be recognized between the pollen mother cells at leptotene stage, which increase in number at zygotene and expand in width at synizesis and they lie in the range 0.5—1 μm. Massive chromatin substance are transferred from one pollen mother cell to another during synizesis. The pre-existing plasmodesmate channels close again at late pachytene. There are no channels from metaphase Ⅰ to tetrad stage. Finally, the relation between the presence of plasmodesmata channels, synizesis and cytomixis were discussed.     

云杉针叶的扫描电镜观察

本文应用扫描电子显微镜,对针叶树云杉的针叶进行了表面结构的观察。结果表明,云杉针叶表面有较厚的角质层,角质层呈条纹状排列。从横切面上看,针叶为四角形,叶的四面均有气孔。云杉的气孔下陷,呈蜂窝状,叶表皮具有瘤状突起物, 这些构造特征,都有利于减少植物体水分的散失。通过对云杉这些结构的观察研究。可以为它的品种改良提供依据。     

rRNA Sequence-Based Scanning Electron Microscopic Detection of Bacteria

A new scanning electron microscopic method was developed for gaining both phylogenetic and morphological information about target microbes using in situ hybridization with rRNA-targeted oligonucleotide probes (SEM-ISH). Target cells were hybridized with oligonucleotide probes after gold labeling. Gold enhancement was used for amplification of probe signals from hybridized cells. The hybridized cells released a strong backscatter electron signal due to accumulation of gold atoms inside cells. SEM-ISH was applied to analyze bacterial community composition in freshwater samples, and bacterial cell counts determined by SEM-ISH with rRNA-targeted probes for major phyla within the domain Bacteria were highly correlated to those by fluorescent in situ hybridization (FISH). The bacterial composition on surface of river sediment particles before and after cell dispersion treatment by sonication was successfully revealed by SEM-ISH. Direct enumeration of bacterial cells on the surface of sonicated sediment particles by SEM-ISH demonstrated that members of Cytophaga-Flavobacterium existed tightly on the surface of particles. SEM-ISH allows defining the number and distribution of phylogenetically defined cells adherent to material surfaces, which is difficult in FISH, and it gives new insight into electron microscopic studies of microorganisms in their natural environment.     

Synthesis of Glucan on the Cell Surface of Streptococcus mutans: Chemical and Scanning Electron Microscopic Studies

The appearance and continuing growth of extracellular material on Streptococcus mutans HS6 cells in sucrose-containing Merthiolated buffer was observed in a scanning electron microscope and was found to be related to the glucan synthesis on the cell and to adherence of the cell to a smooth surface. Cells grown in broth completely deprived of sucrose by invertase (HS6-IV) had a characteristic, slightly rugged surface structure. On incubation of HS6-IV in the sucrose-containing buffer, a few small globular particles appeared on the surface and grew to an irregular shape (globular to fibrilar) after several hours. The increase in the total glucan content of the cells paralleled the growth of the globular material, to which ferritin-conjugated anti-dextran globulin was found to bind. On the cell surface of cells harvested from conventional broth, both small globular and irregular structures, which possibly formed from sucrose in the broth, existed originally and continued to grow during incubation, along with the material newly appearing on the surface. The accumulation of glucan on the cells resulted in their adherence to a glass surface. The inhibition of growth of the extracellular material on the cells by trypsin, dextranase or anti-glucosyltransferase corresponded to the decrease in glucan synthesis and the loss of adhering ability. These results indicated that the material growing on the cell surface was glucan synthesized by glucosyltransferases.     

The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X-Ray Diffraction Studies

Two crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO₃ mobilization from such deposits.     

Scanning Electron Microscopic Studies on Four Species of the Genus Syphacia (Nematoda, Oxyuridae)

The ultrastructure of the head end and surface structure of the cuticle of Syphacia petrusewiczi, S. nigeriana, S. frederici and S. stroma was studied. These species may be easily separated on the basis of the differences in their morphology: S. frederici possesses longitudinal septa on the body surface, a row of denticles on each of the three main teeth, and cervical alae; S. nigeriana has longitudinal septa and denticles but lack cervical alae; S. petrusewiczi has longitudinal septa and cervical alae but lacks denticles; S. stroma lacks these three characters.     

华鲮鳃表面形态结构扫描电镜观察

应用扫描电镜对华鲮Sinilabeor rendahli鳃耙、鳃弓、鳃丝和鳃小片的形态结构进行了观察.鳃耙和鳃弓表面凹凸不平,分布着大量丘突.鳃丝和鳃耙表面有大量粘液细胞分布,鳃丝上皮细胞表面密布微嵴,氯细胞附着在鳃丝表面和鳃小片侧表面.鳃小片薄、表面凹凸不平,垂直排列在鳃丝上.鳃丝和鳃小片的表面形态结构特征有助于提高鱼鳃的气体交换效率.     

A Scanning Electron Microscopic Observations of the Leaves in Some Conifers

Scanning electron microscopic observations of the leaves in some conifers are described. These are hyplocheilie stomata surrounded by different morphological subsidiary cells. In Keteleeria, the lateral wall of larger subsidiary cells possesses prom.inant eutieular globoides. Cuticular semigloboides between the sinuoms epidermal anticlinal walls are most obvious in other epidermis. However the single laver of cushion cells which looated underneath the guard ceils of the abaxial epidermis in Cathaya is discovered. The mesophyll ceils with incurved walls of Cathaya consist mainly of single layer of flat oubical cells flat longi-cubieal cells as of the polytriehaeeous lamcllae, thus it may be designated as mesolamellae. It not only supports the establishment of Cathaya Chun and Kuang as a new genus of the Pinaeeae but also may be another important biosystematical evidence between Cathaya and Pinus. The distribution and polymorphism of foliar solereids in Amentotaxus which are different from leaves of other gymnosperms described. The transfusion tracheids are also different in some ways from other genera.     

豌豆根瘤中细菌的扫描电镜观察

用扫描电镜观察了豌豆根瘤的侵染细胞.结果表明,在这些细胞中有大量的细菌,它们主要是杆状细菌,其次是球形、Y形和T形细菌,其它形状的细菌很少.除了细菌形状不同外,还有一些细菌比较特殊,如有的细菌较长,菌体出现部分收缩并形成一个或一个以上的收缩环,其形状类似一条莲根;有的细菌很大,它的体积是普通细菌的2倍或2倍以上;有的细菌粗细不均匀,端部膨大,呈棒槌状.侵染细胞中有许多小泡,它们大小不同,呈球形.它们存于细菌之间,其中一些小泡还位于细菌的表面上,而且附近细菌的表面有时还有各种隆起.     

Fixation of Platelets for Scanning and Transmission Electron Microscopy

A double fixation method of preparing platelet suspensions for both scanning and transmission electron microscopy is outlined. Prefixation in 0.1% glutaraldehyde allows for immediate preservation of morphologic characteristics induced by experimental procedures, but does not completely destroy platelet surface stickiness. Preservation of surface stickiness allows subsequent production of a platelet pellet for processing for transmission electron microscopy. This pelleting cannot be achieved when higher initial concentrations of glutaraldehyde are used for prefixation. Prefixation in 0.1% glutaraldehyde is also an appropriate initial step for preservation of platelets in suspension for scanning electron microscopy.