花生胚乳细胞化的超微结构观察

花生（ＡｒａｃｈｉｓｈｙｐｏｇｅａｅＬ．）心形胚期的胚乳游离核多瓣裂,或具长尾状结构。胚乳细胞质内有大量线粒体、质体、高尔基体、小泡及少量内质网。中央细胞壁有壁内突。球胚及心形胚期常见胚乳瘤。心形胚晚期,胚乳开始细胞化,胚乳细胞壁形成有３种方式,分别存在于不同的胚珠中：（１）从胚囊壁产生自由生长壁形成初始垂周壁,具有明显的电子密度深的中层,其生长主要靠末端的高尔基体小泡及内质网囊泡的融合。两相邻的自由生长壁末端或其分枝末端相连形成胚乳细胞。（２）核有丝分裂后产生细胞板,细胞板向外扩展并可分枝。间期的非姊妹核间也观察到形成了细胞板。小泡与微管参与细胞板的扩展,高尔基体和内质网是小泡的主要来源。细胞板的扩展末端相互连接,形成胚乳细胞的前身。小泡继续加入细胞板的组成,以后形成胚乳细胞壁。（３）胚乳细胞质中,出现一些比较大的不规则形的片段性泡状结构,它们可能来源于高尔基体小泡,这些片段性泡状结构随机相连形成细胞壁,未见微管参与。胚乳细胞外切向壁及经向壁上有壁内突。     

Cytokinesis in microspore mother cells of Impatiens sultani

Summary Cytokinesis in Impatiens sultani microspore mother cells is simultaneous. It starts with the formation of small ingrowths of the surrounding callosic wall. Next, an incomplete cell plate is formed by fusion of small dictyosome vesicles. The cell plate consists of a network of anastomosing tubules and sacs. Aggregates of fusing vesicles are associated with bundles of microtubules, which are oriented perpendicular to the plane of the future cell walls. In the sacculate parts of the cell plate, some callose is deposited, while the associated microtubules disappear. The cell walls ultimately develop by enlargement of the previously formed wall ingrowths, which successively incorporate the elements of the cell plate. The enlargement and thickening of the walls is not accompanied by a further fusion and incorporation of dictyosome vesicles.     

Polysaccharide Secretion by the Watermelon Stigma

Secretion of the galactose-containing polysaccharide componentof the watermelon stigma exudate was studied using electronmicroscopy cytochemistry and autoradiography. Polysaccharidelocalization using the thiosemicarbazide–silver proteinatemethod stained the Golgi apparatus and secretory vesicles, thecell wall, wall thickenings and extracellular secretion. Thesame result was obtained at anthesis and at 18 h prior to anthesis,which coincides with the period of maximum secretion. Labellingof stigmas in vivo with D-(1-³H) galactose at 20 h prior toanthesis resulted in different labelling patterns after 2 h(18 h prior to anthesis) and 20 h (anthesis). At 18 h priorto anthesis label was present in the Golgi apparatus and secretoryvesicles, the cell wall and wall thickenings. By anthesis labelhad accumulated in the extracellular secretion in addition tothe Golgi apparatus, secretory vesicles, cell wall and wallthickenings. The results suggest that the polysaccharide componentof the stigma exudate is produced in the Golgi apparatus andsecreted via the cell wall and wall thickenings. Citrullus lanatus Thumb., Matsum and Nakai, watermelon, autoradiography, stigma, secretion, cytochemistry, polysaccharide     

Pollen--stigma Interaction in the Leguminosae: the Secretory System of the Style in Trifolium pratense L.

The canal that traverses the upper part of the style of Trifoliumpratense is derived lysigenously. The core tissue of the veryyoung style consists of elongated cells similar to those ofthe transmitting tissue of solid-style families such as theSolanaceae; as the style matures, these cells separate to formthe canal, which receives secretions both from the core tissueand the inner wall cells. The early secretion of proteins intothe intercellular spaces is associated with the presence ofparamural bodies (lomasomes) in the adjacent cells. In the cellsin the immediate vicinity of the canal, vesicles, probably derivedfrom the Golgi system enlarge during later development and accumulatea protein-carbohydrate content, which is later passed into thecytoplasm where it forms densely packed fibrillar nodules. Withthe dissolution of the cell membranes, this material is passedinto the canal, where it is progressively diluted by continuedingress of water until the cavity reaches its final volume. Leguminosae, Trifolium pratense L., pollen—stigma interaction, self-incompatibility, stylar secretion, protein secretion     

Histogenesis of the transmitting tract in Strelitzia reginae

Organisation and development of the stigmatic, stylar and ovarian parts of the transmitting tract in Strelitzia reginae were evaluated. They were characterised by 1) cell shape, 2) appearance of distal cell wall, 3) type of plastid, 4) and vacuolar system. The long stigmatic trichomes have a secondary irregular wall layer separated from the primary wall. Cell structures include pleomorphic plastids with vesiculated thylakoids and frequently a crystal or a lipidic globule. In early stages of bud development the extensive endoplasmic reticulum (ER) is smooth, whereas it is mainly rough in older buds. Coated vesicles are frequent, as are dictyosomes. Prominent invaginations along the plasma membrane contain floccular deposits in the older flower buds. These deposits are similar in structural appearance to material in the large vacuoles. The basal part of the stigma has wedge-shaped cells with wall ingrowths. Three stages of stigmatic secretion during the development were characterised. The stylar canal is initially narrow but widens subsequently. The cuticle is detached and the apical cell walls show a fringed surface; from this wall inbuddings develop shortly before anthesis. At this stage sheets of rough ER are evident in the cell cortex. The plastids have a few vesiculated thylakoids, proteinaceous crystals and starch grains. The epithelial cells of young buds have numerous vacuoles, the volume of which decreases in more mature cells. The stylar canal is filled with a secretion at all stages of bud development. The face of the ovarian transmitting tract, lining the placenta, is smooth in young buds but lobed in older ones due to the division pattern of the epithelial cells. These cells are large, elongated and culumnar as young but narrow and wedge-shaped when more mature. Cell wall inbuddings are formed late during bud development.     

荞麦柱头、花柱的结构及ATP酶的超微细胞化学定位

利用超薄切片结合ATP酶定位技术,研究了荞科柱头及花柱的结构。结果表明,成熟的荞麦柱头表面无乳突细胞,柱头细胞的细胞壁存在发达的壁内突,花柱为实心型无引导组织,柱头表面的细胞壁根据电子密度的不同可划分为3层,最外一层电子密度最大,最内一层电子近透明,并形成壁内突的结构,柱头表面和花柱细胞的质膜上ATP酶的活性较高,表明成熟的柱头和花柱细胞物质代谢和运输十分活跃,成熟的柱头和花柱细胞中有丰富的蛋白质和多糖类物质。     

AN ULTRASTRUCTURAL STUDY OF TRANSMITTING TISSUE DEVELOPMENT IN THE PISTIL OF LILIUM LEUCANTHUM

A study of developing transmitting tissue of Lilium Leucanthum pistils was undertaken in order to correlate structure with function. Lining the stylar canal are stigmatoid cells which contain a secretory zone consisting of a labyrinth of wall ingrowths characteristic of transfer cells. The functional feature of the labyrinth is a high surface-to-volume ratio that facilitates an intensive transmembrane flux of solutes. Stigmatoid cells in various stages of development and maturation have been investigated with the aid of electron and light optics in conjunction with cytochemical techniques. During development of the secretory zone, vesicles, formed by hypersecretory dictyosomes, fuse with the plasma membrane and contribute their contents to the growing wall. The pattern of secretory zone development is basipetal and is associated with initiation of chemotropism. In a mature pistil large crystals, having a basipetal pattern of development, and sensitive to protease, can be observed in the cytoplasm of stigmatoid cells. At anathesis, degradation of the crystal can be observed in the cells of the stigma surface and progresses basipetally as the pistil ages. The role of the crystal is uncertain. Immature pistils cultured in the presence of labeled proline take up the label which at maturity of the pistil is transferred to the canal of the pistil. The label is found in the crystals and the secretory zone of the stigmatoid cells. Pollen tubes growing in the canal of a labeled pistil take up the label.     

The Anatomy, Histochemistry and Ultrastructure of Stigmas and Styles in Commelinaceae

The anatomy and ultrastructure of stigmas in 37 species of 13genera of Commelinaceae are described. The stigmas are papillate,papillae forming a dense fringe of cells around the mouth ofthe stylar canal in most species. The papillar cell wall iscovered by an unstructured cuticle of variable thickness andis of variable thickness because of small wall ingrowths. Thecuticle and the external surface of the papillar cell wall arevariably disrupted, particularly in the mid and basal regionsof the cell. This was not found in species of the genus Aploleiaor Callisia. The cell cytoplasm possesses all major organellesexcept chloroplasts and each cell is vacuolate. In all species except Aploleia mulitiflora the style comprisesan epidermis, a cortex and a hollow, tripartite canal whichis continuous into the ovary cavity. The three vascular strandsare positioned at the apex of each canal lobe. The canal cellsare elongate and tabular and the wall abutting the canal hasingrowths. The style in Aploleia is solid and the transmittingtissue comprises cells whose walls are electron opaque. Thecytoplasms of both types of cell are similar in content althoughthere is a single, large vacuole in canal cells and many smallvacuoles in transmitting tissue. The morphology, position and histochemistry of stigmatic andstylar exudate was similar in all ‘wet’ stigmas.Most of the exudate originates from the stylar canal althoughsignificant contributions are made by the papillae in stigmasof Coleotrype, Dichorisandra and Thyrsanthemum. There is no apparent relationship between stigma structure andthe presence of self-incompatibility. Stigma papillae, stylar canal, transmitting tissue, Commelinaceae     

Ultrastructure of transfer cells in spontaneous nodules of alfalfa (Medicago sativa)

Summary Spontaneous nodules were formed on the primary roots of alfalfa plants in the absence ofRhizobium. Histologically, these white single-to-multilobed structures showed nodule meristems, cortex, endodermis, central zone, and vascular strands. Nodules were devoid of bacteria and infection threads. Instead, the larger cells were completely filled with many starch grains while smaller cells had very few or none. Xylem parenchyma and phloem companion cells exhibited long, filiform and branched wall ingrowths. The characteristic features of both types of transfer cells were polarity of wall ingrowths, high cytoplasmic density, numerous mitochondria, abundant ribosomes, well-developed nucleus and nucleolus, and vesicles originated from rough endoplasmic reticulum. These results were compared with normal nodules induced byRhizobium. Our results suggest that xylem parenchyma and phloem companion transfer cells are active and probably involved in the short distance transport of solutes in and out of spontaneous nodules. Since younger nodules showed short, papillate, and unbranched wall ingrowths, and older tissue showed elongated, filiform and branched wall ingrowths, the development of wall ingrowths seemed to be gradual rather then abrupt. The occurrence of both type-A and -B wall ingrowths suggests that phloem companion transfer cells may be active in loading and unloading of sieve elements. Since there were no symbiotic bacteria and thus no fixed nitrogen, it is tempting to speculate that xylem parenchyma transfer cells may be re-transporting accumulated carbon from starch grains to the rest of the plant body by loading xylem vessels. Fusion of ER-originated vesicles with wall ingrowth membrane indicated the involvement of ER in the membrane formation for elongating wall ingrowths. Since transfer cells were a characteristic feature of both spontaneous andRhizobium-induced nodules, their occurrence and development is controlled by the genetic make-up of alfalfa plant and not by a physiological source or sink emanating from symbiotic bacteria.Abbreviations ATP adenosine triphosphate - ATPase adenosine triphosphatase - EH emergent root hair - EM electron microscope - Nar nodulation in the absence of Rhizobium - RT root tip - RER rough endoplasmic reticulum - YEMG yeast extract mannitol-gluconate     

Immunogold localization of the cell-wall-matrix polysaccharides rhamnogalacturonan I and xyloglucan during cell expansion and cytokinesis inTrifolium pratense L.; implication for secretory pathways

We have localized two cell-wall-matrix polysaccharides, the main pectic polysaccharide, rhamnogalacturonan I (RG-I), and the hemicellulose, xyloglucan (XG), in root-tip and leaf tissues of red clover (Trifolium pratense L.) using immunoelectron microscopy. Our micrographs show that in both leaf and root tissues RG-I is restricted to the middle lamella, with 80–90% of the label associated with the expanded regions of the middle lamella at the corner junctions between cells. Xyloglucan, however, is nearly exclusively located in the cellulose-microfibril-containing region of the cell wall. Thus, these cell-wall-matrix polysaccharides are present in distinct and complementary regions of the cell wall. Our results further show that during cell expansion both RG-I and XG are present within Golgi cisternae and vesicles, thus confirming that the Golgi apparatus is the main site of synthesis of the non-cellulosic cell-wall polysaccharides. No label is seen over the endoplasmic reticulum, indicating that synthesis of these complex polysaccharides is restricted to the Golgi. The distribution of RG-I and XG in root-tip cells undergoing cell division was also examined, and it was found that while XG is present in the Golgi stacks and cell plate during cytokinesis, RG-I is virtually absent from the forming cell plate.Abbreviations ER endoplasmic reticulum - RG-I rhamnogalacturonan I - XG xyloglucan     

Ultrastructural characteristics of « Diplotaxis erucoides (L.) DC. » suspensor

Abstract

The development and general morphology of Diplotaxis erucoides (L.) DC. suspensor is of the « Onagrad Type », « Alyssum Variation ». Maximum growth of the suspensor occurs from the globular to the early heart stage of embryo development. The suspensor starts then to degenerate disintegrating shortly after the torpedo stage of the embryo.

The wall ingrowths of the long, tapering, basal cell are especially abundant at the cell's micropilar pole which is closely surrounded by well developed wall ingrowths formed by the endosperm. Wall ingrowths and plasmodesmata are present on the suspensor cells cross walls with the exception of the cell closest to the embryo. No such structures in fact are present on the walls separating this last cell both from the embryo and from the rest of the suspensor. Wall ingrowths are generally associated with numerous, large, mitochondria.

The morphological data seem to indicate that absorption and transport of nutrients from the surrounding tissues is a main function of the suspensor. The possibility of an elaborative and secretory function of this structure is discussed.     

Vesicle production and fusion during lobe formation inMicrasterias visualized by high-pressure freeze fixation

Summary Two different types of Golgi vesicles involved in wall formation can be visualized during lobe growth inMicrasterias when using high-pressure freeze fixation followed by freeze substitution. One type that corresponds to the dark vesicles (DV) described in literature seems to arise by a developmental process occurring at the Golgi bodies with the single vesicles being forwarded from one cisterna to the next. The other vesicle type appears to be produced at thetrans Golgi network without any visible precursors at the Golgi cisternae. A third type of vesicle, produced by median andtrans cisternae, contains slime; these are considerably larger than those previously mentioned and they do not participate in wall formation. The distribution of the two types of cell wall vesicles at the cell periphery and their fusion with the plasma membrane are shown for the first time, since chemical fixation is too slow to preserve a sufficient number of vesicles in the cortical cytoplasm. The results indicate that fusions of both types of vesicles with the plasma membrane are possible all over the entire surface of the growing half cell. However, the DVs are much more concentrated at the growing lobes, where they form queues several vesicles deep behind zones on the plasma membrane thought to be specific fusion sites. The structural observations reveal that the regions of enhanced vesicle fusion correspond in general to the sites of calcium accumulation determined in earlier studies. By virtue of the absence of the DVs in the region of cell wall indentations the second type of wall forming vesicle appears prominent; they too fuse with the plasma membrane and discharge their contents to the wall.     

The Structure of the Canal Cell in the Style of Lilium regale

The fine structure of canal cell in the style of Lilium regale has been observed under light and electron microscopes by OMA thin section method and ultra-thin section method respectively. The ultrastructural specialization of the canal cells during their functional stages may be characterized as follows: 1. The cell wall on the secretory face of the canal cell has numerous branched ingrowths extending into the cytoplasm, and the plasmalemma closely follows the contours of the ingrowths to form the wall-membrane apparatus. This pattern of distribution of plasmalemma increases the surface-volume ratio of the cell to facilitate the secretion of solutes out of the cell. 2. The cell wall under the thin layer of cuticle on the outside of the secretory face is digested starting from the outer part and gradually extending to the inner part to form a large space, the temporary secretory layer. During the secretion of products by the cell, the thin layer of cuticle becomes ruptured in many places and finally disappeared. Therefore the cell wall of the secretory face remains a thin layer only at that time. The change of the layers of the cell wall is involved in the mechanism of cell secretion. 3. The ultrastructural characteristics of the canal cell indicate that this cell is active in synthesis, intercellular transport and energyn metabolism. Some of the major facts seen in all cases included the highly lobing of nucleus, abundance of endoplasmie reticulum throughout the cytoplasm and well developed mitochondria, dictyosomes and polysomes. During the secretory stage of the cell, mitochondria apparently concentrate near the wall-membrane apparatus. 4. There are numerous granular and vesicular structures near the wall-membrane apparatus on the secretory face, especially at the space between wall ingrowths and plasmalemma. The presence of these granular and vesicular structures is thought to be related to the secretory function of the cell. According to the specialized characteristics the canal cell is evidently a typical transfer cell of the secretory type.     

鹅掌楸属植物引导组织和花粉管生长

应用光学显微镜和常规石蜡切片技术研究了鹅掌楸属（ＬｉｒｉｏｄｅｎｄｒｏｎＬ．）两种植物雌蕊引导组织的分布和个体发育,引导组织是由心皮边缘或内表面的表皮细胞层或亚细胞层发育形成,是由一层细胞组成的连续层,覆盖干柱头、花柱道和珠柄的表面,引导组织的细胞形态学因其所在部位不同而有差异。在电境水平上研究了柱头和花柱引导组织的超微结构,引导组织细胞是分泌型的传递细胞,其分泌面发育了明显的壁内突,细胞质中富含内质网、多聚核糖体、各种小泡、高尔基体和线粒体,大液泡通常远离分泌面。文中还探讨了花粉管生长后引导组织的变化。     

Transfer Cells in Suspensur and Endosperm during Early Embryogeny of Vigna sinensis

During early embryogeny, structural differentiation of the suspensor and endosperm can be observed with the formation of cells with wall ingrowths. In the early proembryo stage, wall ingrowths are seen only on the boundary walls of the embryo sac around the proembryo and at the chalazal end. Later, ingrowths appear in the outer walls of the basal suspensor cells and some wall ingrowths also begin to develop in the outer walls of cellular endospermic cells adjacent to the nucellar cap and the inner integumentary tissues. The suspensor appears to remain active throughout the differentiation stages. Two regions can be clearly distinguished in the suspensor: a basal region and a neck region. Wall ingrowths appear to form only in the cells of the basal region. During the development of the cellular endospermic sheath, its cell number and size both increase slightly. Later, these cells rapidly become separated from each other. Those endospermic cells that abut directly onto the integumentary tissues also develop wall ingrowths. In the region of the fluid endosperm, wall ingrowths are especially abundant in the boundary walls on the ventral side of the embryo sac. The possible pathway of nutrient flow to the developing embryo is discussed.     

Polarized microtubule deposition coincides with wall ingrowth formation in transfer cells ofVicia faba L. cotyledons

Summary The epidermal transfer cells in developingVicia faba L. cotyledons are highly polarized. Extensive wall ingrowths occur on their outer periclinal walls and extend part way down both anticlinal walls. This ingrowth development serves to increase the surface area of the plasma membrane and thus maximize porter-dependent uptake of sugars from the seed apoplasm. In contrast, the inner periclinal walls of these transfer cells do not form wall ingrowths. We have commenced a study of the mechanisms responsible for establishing this polarity by first analysing the microtubule (MT) cytoskeleton in developing transfer cells. Thin sections of fixed cotyledons embedded in methacrylate resin were processed for immunofluorescence microscopy using monoclonal anti--tubulin and counterstained with Calcofluor White to visualize wall ingrowths. In epidermal cells of young cotyledons where wall ingrowths were yet to develop, MT labelling was detected around all cortical regions of the cell. However, in cells where wall ingrowths were clearly established, MT labelling was detected almost exclusively in cortical regions adjacent to the wall ingrowths. Little, if any, MT labelling was detected on the anticlinal or inner periclinal walls of these cells. This distribution of MTs was most prominent in cells with well developed wall ingrowths. In these cells, a subpopulation of MTs were also detected emanating from the subcortex and extending towards the wall ingrowth region. The possible role of MT distribution in establishing transfer cell polarity and wall ingrowth formation is discussed.Abbreviations MT microtubule     

Ultrastructural research on cell wall regeneration by cultured pollen protoplasts of Lilium longiflorum

Summary Protoplasts from pollen grains of Lilium longiflorum regenerate amorphous cellulosic cell walls in culture, during which some precursors of cellulose are polymerized, thus producing progressively harder cellulosic cell walls as the period of culture continues. It is presumed that the components of the cell wall regenerated during 1 week in culture differ from those of the intine of the pollen grain wall. The regenerated cell wall is formed by means of large smooth vesicles; in addition, numerous coated vesicles and pits aid in wall regeneration. The pollen tube that germinates from the 8-day-old cultured protoplast has numerous Golgi bodies and many vesicles which build the pollen tube wall. The tube wall has two layers just like a normal pollen tube wall.     

Elektronenmikroskopische Untersuchungen von Differenzierungsvorgängen bei Moosen

Summary In meristematic cells of the gemma of Riella helicophylla and in young bud cells from the protonema of Funaria hygrometrica the cell plate is formed by fusion of small vesicles originating from the Golgi apparatus. These spherical vesicles of about 0.1 m diameter have an electron dense centre, probably consisting of pectic substances or their precursors. The endoplasmic reticulum producing multivesicular bodies participate in cell plate formation too. Another cytoplasmic component forming the cell plate are coated vesicles, the origin of which is the Golgi apparatus and perhaps also the endoplasmic reticulum. In view of these observations the question of whether the endoplasmic reticulum or the Golgi apparatus forms the cell plate must be answered in this way: both endoplasmic reticulum and Golgi apparatus supply material for growth of the cell plate. Multivesicular bodies, coated vesicles and other small vesicles of unknown nature participate in the formation of the primary wall.

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Zum Teil finanziert mit Sondermitteln des Landes Niedersachsen an Prof. Dr. M. Bopp.     

Improved preservation of the form and contents of wall vesicles and the golgi apparatus in freeze substituted hyphae ofSaprolegnia

Summary Secretory vesicles involved in cell wall synthesis (wall vesicles) and the Golgi apparatus have been compared in conventionally fixed and freeze substituted hyphae of the oomycete fungusSaprolegnia ferax. Wall vesicles freeze substituted in various fluids range from spherical to tubular and contain an intensely staining, phosphorous rich matrix. In contrast diverse conventional fixations cause artefactual constrictions in most tubular vesicles and loss of their intensely staining contents. These data are interpreted to show the existence of an intravesicular skeletal system, with cellular regulation, to determine vesicle morphology and intravesicular synthesis of a hypothetical phosphorylated glycolipid cell wall precursor. Whilst freeze substitution gives superior preservation of wall vesicle morphology, it does not demonstrate any preferential association between wall vesicles and microtubules thus suggesting that microtubules are only indirectly involved in wall vesicle transport. Freeze substitution is superior to conventional fixation for analysis of the Golgi apparatus because it uniquely reveals both differentiation of a specific single cisterna in each Golgi body and greater differences in membrane thicknesses throughout the endomembrane system.     

Characterization of fibrous compound of Golgi vesicles in tapetal cells ofDelphinium

Summary It was shown that Golgi structures abundantly appearing in tapetal cells ofDelphinium Ajacis L. developing anthers, prior to meiocytes meiosis, show a fine fibrous material within their vesicles. At the time of the formation of tapetal cell wall this fibrous component, released by an exocytotic process, is incorporated into the cell wall. The membrane of dictyosomes derived vesicles participates in the development of plasma membrane. Fibrous material appears to be morphologically similar to the fibrils of tapetal cell wall; this cell wall gives a positive reaction for cellulose and pectins, as visible in the light microscope. Moreover, the fibrous and pectinase resistant compound of dictyosomes derived vesicles and the fibrils of cell wall disappear partly after cellulase digestion which proves their cellulosic character. On the other hand pectinase treatment as well as ruthenium red staining suggest associated with cellulose pectins within Golgi vesicles.