漆树茎次生韧皮部超微结构的研究

本文叙述了漆树茎次生韧皮部各组成分子的超微结构。在漆树茎的次生韧皮部中,各个组成分子除了有与一般双子叶植物类似的超微结构外,筛管分子、伴胞、韧皮薄壁组织细胞,丹宁细胞和射线细胞中都含有嗜锇滴。其中电子密度较大的嗜锇滴与乳汁道分泌细胞中的相似,有相同的分布规律,并都有通过质膜和细胞壁向外运输的趋势。因此,我们认为,在漆树中,韧皮部的各个组成分子除了为乳汁道分泌细胞提供正常的营养物质外,同时也可能提供合成分泌物的原料或前体物质,而这些原料或前体物质是通过质膜和细胞壁向乳汁道分泌细胞转运的。此外,在成熟筛管分子的筛孔周围都衬有很厚的胼胝质,并为一些电子不透明的P—蛋白质所堵塞,这种现象可能是由于切割造成筛分子内部压力的消除和植物体产生损伤反应的结果。     

热带落叶树降香黄檀次生韧皮部薄壁组织细胞超微结构的季李 …

利用透射电子显微镜技术研究了热带落叶树降香黄檀（Ｄａｌｂｅｒｇｉａ ｏｄｏｒｉｆｅｒａ Ｔ．Ｄｈｅｎ）末端小枝次生韧皮部韧皮和射线薄壁组织细胞的季节变化。这些变化主要表现为细胞内贮藏物质（其中包括中央液泡中的贮藏蛋白质,质体中的淀粉粒、类脂球和铁蛋白,以及圆球体中的类脂类）的周期性的积累和消耗。降香黄檀在冬季落叶期不出现在温带落叶树木中看到的与抗寒有关的若干细胞学改变。降香黄檀也象温带树木一样,薄     

热带落叶树降香黄檀次生韧皮部薄壁组织细胞超微结构的季节变化

研究了ＵＶ－Ｂ辐射对广东省南亚热带森林木本植物九节、鸭脚木、猴耳环、半枫荷、山乌桕入绿化树种大叶合欢幼苗生长的影响。实验结果表明,ＵＶ－Ｂ辐射降低叶片光合色素的含量;显著降低幼苗的净光合速率、蒸腾速率和气孔导度;降低干物质的增长;抑制大叶合欢幼苗要根瘤的形成。     

降香黄檀着叶期和无叶期次生韧皮部筛分子的超微结构

利用透射电镜技术研究了生长在海南岛的热带落叶树降香黄檀(Dalbegia odorifera T.Chen)1—2年生枝条着叶期和无叶期次生韧皮部筛分子的超微结构,并就这两个时期的筛分子进行了比较。着叶期每个成熟筛分子内有一个带尾的纺锤形P-蛋白质体,主体由稠密而散乱的P-蛋白质细纤维组成,尾部呈结晶状;筛分子具有横向端壁和单筛板,在邻近筛板处,细胞壁向筛分子腔内形成明显的突起。无叶期仍然保持着与着叶期大致相同厚度的有功能韧皮部,筛分子具有正常的原生质体,P-蛋白质和筛板孔的结构也与着叶期的相同,但筛分子内有较多的淀粉粒和囊泡。     

金松茎次生韧皮部的解剖

在光学显微镜和扫描电子显微镜下,金松茎次生韧皮部的结构,主要特征为:(1)轴向系统由筛胞、韧皮薄壁组织细胞、蛋白质细胞及韧皮纤维组成;径向系统为单列,稀二列的韧皮射线构成。(2)筛胞径向壁上嵌埋有许多草酸钙结晶。(3)韧皮纤维仅一种类型,径向排列1—6个细胞宽的切向带,两带之间筛胞与韧皮薄壁组织细胞层数不规则。通过我们的研究结果,支持金松属可从杉科中分离出来成立金松科的主张。     

红豆杉科次生韧皮部的比较解剖

在光学显微镜及扫描电镜下,比较观察了红豆杉科Ｔａｘａｃｅａｅ５属即红豆杉属Ｔａｘｕｓ,白豆杉属Ｐｓｅｕｄｏｔａｘｕｓ、穗花杉属Ａｍｅｎｔｏｔａｘｕｓ,榧树属Ｔｏｒｒｅｙａ和澳洲红豆杉属８种植物茎次生韧皮部的结构。其主要结果为：红豆杉科植物茎次生皮部由轴向系统和径向系统两部分构成。轴向系统由筛胞,韧皮薄壁组织细胞,蛋白细胞及韧皮纤维组成;径向系统由韧皮射线构成,但是,在横切面上,各个组成分子的层次有     

降香黄檀次生韧皮部薄壁组织细胞液泡蛋白质的形成和积累的超微结构研究

热带豆科树木降香黄檀（Ｄａｌｂｅｒｇｉａｏｄｏｒｉｆｅｒａ）落叶时期末端小枝次生韧皮部薄壁组织细胞的中央液泡中有大量的贮藏蛋白质。用透射电镜技术研究了这些蛋白质的形成和积累。在这些细胞的周缘细胞质中有丰富的游离核糖体和许多粗糙内质网（ＲＥＲ）。在这些核糖体之间,总是分散着纤维状物质,有时还出现一些类似液泡蛋白质的结构。常常看到与ＲＥＲ相连的含有稀疏纤维状物质的小泡,以及含有类似液泡蛋白质的形状不规则的小泡和含有更多类似液泡蛋白质的光滑小泡。从连接ＲＥＲ的小泡到形状不规则小泡,再到光滑小泡,可能存在个体发生的连续性。通过内吞作用细胞质中的纤维状物质和核糖体以及其它结构被并入上述３种小泡。光滑小泡通常与中央液泡的膜融合而释放其内含物到液泡中。     

十齿花次生木质部和次生韧皮部的解剖学研究

对十齿花的次生木质部和次生韧皮部结构进行了观察,并与卫矛科其它８属植物的木质部作子下齿花次生木质部和次生韧皮部的主要特点是;木质部导管分子相对较长,其末端倾斜,具梯状穿孔板,由１４个横隔组成。纤维和纤维管胞均有横隔。韧皮部筛管分子相对较短,其端壁水平或略倾斜,具单筛板,缺少纤维。     

白皮松次生韧皮部蛋白细胞的细胞学研究

本文重点观察白皮松（Pinus bungeana)次生韧皮部中蛋白细胞不同发育时期的超微结构,白披松次生韧皮部由筛胞,轴向薄壁组织,径向片和射线组成,大多数直立射线细胞与径向片薄壁细胞是蛋白细胞,虽然这两类蛋白细胞在形状和分布上有所不同,但它们都具有下列的细胞学特征：细胞质浓厚,线粒体丰富,具核糖体,粗糙内质网和大的细胞核;细胞核常呈凹陷形;蛋白细胞含有淀粉粒,但与其它的韧皮部薄壁细胞相比,蛋白细胞的淀粉含量较少,上述细胞结构特征显示出蛋白细胞具有旺盛的生理活性,蛋白细胞与其它薄壁细胞的主要区别是：蛋白细胞与相邻的筛胞以单侧筛域相联系,当筛胞死亡时也一同死去。     

Ultrastructure of Sieve Elements in Secondary Phloem of Dalbegia odorifera During Leaf-Bearing and Leaf-Absent Period

Ultrastructures of sieve elements of secondary phloem of 1–2 year old branchlet of tropical deciduous tree Dalbegia odorifera T. Chen growing on Hainan Island were studied under transmission electron microscope and a comparation was made between the sieve elements in leaf-bearing and leaf-absent period. During the leaf-bearing period, there was a tailed spindleshaped P-protein body in each mature sieve element. The main part of the P-protein body con sisted of a disordered fine fiber mass with two crystalline tails. The sieve elements had horizontal end walls with simple sieve plate. The inner layers of the wall near the sieve plate appeared intumescent, protruding into the sieve element lumen. During the leaf-absent period, a functional phloem remained about the same thickness as that during the leaf-bearing period. The sieve elements in the leaf-absent period contained normal protoplasts and the P-protein and the sieve plate pores had the same structures as those during the leaf-bearing period. More starch grains and vesicles were found in sieve elements in the leaf-absent period.     

Another View of the Ultrastructure of Cucurbita Phloem

The primary phloem of young internodes of Cucurbita maxima wasstudied with the electron microscope. Phloem parenchyma cellsare highly vacuolated and contain nuclei, endoplasmic reticulum,ribosomes, mitochondria, chloro-plasts, and occasional dictyosomes.As compared with parenchyma cells, the most distinctive featuresof companion cells are their extremely dense cytoplasm, lowdegree of vacuolation, lack of chloroplasts, and numerous sieve-elementconnexions. Companion cells contain plastids with few internalmembranes. At maturity the enucleate sieve element is linedby a plasmalemma, one or more cistema-like layers of endoplasmicreticulum, and a membrane which apparently delimits the parietallayer of cytoplasm from a large central cavity. In OsO_4–-andglutaraldehyde-fixed elements, the central cavity is traversedby numerous strands, which run from cell to cell through thepores of sieve plates and lateral sieve areas, and which arederived ontogenetically from the slime bodies of immature cells.Numerous normal-appearing mitochondria are present in the parietallayer of cytoplasm. The pores of sieve plates and lateral sieveareas are lined with cytoplasm. The ultrastructural detailsof young sieve elements differ little from those of other youngnucleate cells. During sieve-element development, the sieveelement increases in vacuolation. At the same time, slime bodiesdevelop in the cytoplasm. With glutaraldehyde fixation, thesebodies often exhibit a double-layered limiting membrane. Asthe sieve element continues to differentiate, the slime bodiesincrease in size and the parietal layer of cytoplasm becomesvery narrow. Presently, the slime bodies begin to disperse andtheir contents fuse. This phenomenon occurs in the parietallayer of cytoplasm, while the latter is still delimited fromthe large central vacuole by a distinct tonoplast. The initiationof slime-body dispersal more or less coincides with perforationof the pore sites, and many pores are traversed by slime earlyin their development. Before slime-body dispersal, all dictyosomesand associated vesicles disappear from the cytoplasm. Eventually,the tonoplast diappears and the slime becomes distributed throughoutthe central cavity in the form of strands. Nuclei and ribosomesdisappear before breakdown of the tonoplast. Sieve elementsare connected with companion cells and parenchyma cells by plasmodesmata.     

Comparative Anatomy of Secondary Phloem in Celastraceae

A comparative anatomical study on the secondary phloem of 5-genera, 10 species in Celastraceae was carried out. Based on the phloem structure characters, 3 phloem types were observed. In type Ⅰ , as seen in 5 species of Euonymus, the sieve-tube elements have more inclined end walls and numerous sieve areas (compound sieve plates), phloem rays are almost uniseriate. Type Ⅱ is seen in Celastrus and Tripterygium. It has relatively short sievetube elements, slight inclined end wall and sparse number of sieve areas: the phloem fiber is not lignified and ray is multiseriate. Type Ⅲ is observed in Dipentodon and Perrottetia, the sieve-tube elements are with simple sieve plate, the end wall is almost transverse, there are sclereid and fiber groups in the nonfounctional phloem, and phloem rays are uniseriate or biseriate.     

Anatomical Studies on Secondary Xylem and Secondary Phloem of Dipentodon sinicus

The anatomy of secondary xylem and secondary phloem in Dipentodon sinicus Dunn a precious and protected plant in China was studied, and compared with the wood anatomy of 8 other genera in Celastraceae. The main characteristics of this genus were described as follows: vessel members length were relatively long with scalariform perforations in oblique end walls, which were formed by 14 (9--28) bars. Intervessel pits possessed scalariform pattern. Libriform fibres and tracheid-fibres were septate. The sieve tube elements of the secondary phloem were relatively shorter, with simple sieve plates in the slightly inclined to almost horizontal end walls. There was no obvious boundary between the functional and non-functional phloem. In the Baileyan sense, the secondary xylem possessed a lower level of specialization, and displayed an obviously primitive and conservative character. In contrast, the secondary phloem possessed a higher level of specialization and displayed advanced characters. Therefore, the phylogenetic evolution between xylem and phloem was not synchronous in this genus. The result provided a novel pattern in the development of xylem and phloem structure which has not been noticed before.     

竹子节部“韧皮部结”的发育与超微结构

The development, cytological characters and ultrastructure of phloem ganglion in the nodal region of Phyllostachys edulis (Carr.) H. de Lehaie, a most economically important bamboo, were investigated and the possible physiological function of this special structure was proposed. The phloem ganglion derived directly from procambium is situated at the sites where the vascular bundle forks and is present in pairs. The phloem ganglion is spindle-like in appearance and usually consists of 4 to 6 layers. Two kinds of cells in the ganglion could be distinguished. In the middle, there are two layers of filiform cells with pointed ends so that there are no normal sieve plates. Nevertheless, there are many pits on the lateral wall of the filiform cells. The other type of cells located at both ends of the spindle which possess an intermediate form between the filiform cell and the normal sieve tube. The walls of these cells towards the filiform cells are strongly convex forming a special sieve plate. Ultrastructure study showed that cells in the ganglion are connected by enriched plasmodesma. During early differentiation, the paramural body and the ingrowth of cell wall could be observed. It indicates that the cells of phloem ganglion have the character of transfer cells. The organelles in the mature cells are mainly plastids with abundant accumulation of proteins of crystalline structure. The above-mentioned results suggest that the physiological function of the phloem ganglion is closely related with substance transport.      

竹子节部“韧皮部结”的发育与超微结构

研究了中国最为重要的经济竹种毛竹（Ｐｈｙｌｌｏｓｔａｃｈｙｓ ｅｄｕｌｉｓ （Ｃａｒｒ．）Ｈ．ｄｅ Ｌｅｈａｉｅ）节部“韧皮部结”的个体发育、构成该结构细胞的形态学特征及其超微结构,探讨了该结构可能的生理功能。“韧皮部结”的发育直接来源于原形成层,发生在维管束分叉处,一般成对出现。“韧皮部结”外形呈纺锤体状,一般由４～６层细胞形成叠生构造。构成“韧皮部结”的细胞可以区分为两类,一类是位于纺锤体中部     

Anatomical Studies on Secondary Phloem of Pinus bungeana

This paper deals with structures of the secondary phloem of Pinus bungeana Zucc. The sieve cells lived for only one growing season. Most of them formed in spring and summer and then died in the end of winter. However, some of them formed in autumn and died eventually in the end of next spring. Two types of albuminous cells: type A and type B were seen in radial plates and rays, which possessed the following common characteristics, there were unilateral sieve area connections between these and the sieve cells. These cells had larger nuclei, denser cytoplasm with abundant mitochondria and rich RNA-protein. Their death closely followed that of the sieve cells. Type A albuminous cells differed from type B in that the former collapsed before the contents of sieve cells accompanied with it dissppeared. But, type B did not collapse until complete disappearance of the contents of sieve cells. The cytological characteristics of albuminous cells, the relationship between radial plates and rays, and possible physiological significance are also disscussed.     

Anatomical Studies on Secondary Phloem of Euonymus bungeanus

The anatomical structures, especially the type, distribution and arrangement of the constituent elements in the secondary phloem of Euonymus bungeanus Maxim. have been studied. The results showed that the secondary phloem was thicker, consisted of sieve-tube elements, companion ceils ,phloem parenchyma cells ,secretory ceils and rays. Sieve-tube elements, phloem parenchyma cells and secretory cells were alternately arranged in tangential bands, forming a conspicuous zone-like constitution. There was no obvious boundary between the functional phloem and the non-functional phloem. Sieve-tube elements were long, slender cells with very oblique end walls and compound sieve plates. Sieve areas on lateral wall were highly differentiated. Companion cells were triangular in transection and slender in radial section. Mostly,two or three companion cells stayed along with one sieve-tube element. In the functional phloem, phloem parenchyma cells were also slender, containing a few starch grains;but in the nonfunctional phloem they enlarged and contained abundant starch grains. Secretory cells were longer than sieve-tube elements, consisting of rubber-like material. Rays were uniseriate. Finally, the authors also discussed the phylogenetic position of E. bungeanus, which may provide some references for further study of the classification of different genera of Celastraceae.     

Ultrastructure of Secretory Cells in the Phloem of Mimosa pudicaL.

The secretory cells arc a prominent component of the phloemtissue of Mimosa pudica L. They form longitudinal files in whichthe common end walls of the cells are perforated. The originof the perforations in relation to protoplast differentiationwas the objectof the study. As the cells emerge from the meristematicstate, portions of cytoplasm including some organelles aretransferredinto the central vacuole and are apparently lysed. This phenomenonis accompanied by an accumulation of flocculent material, possiblythe secretory product referred to in the literature as a carbohydrate.The tonoplast ceases to be definable so that the flocculentmaterialand degraded and non-degraded protoplast componentsare intermingled inthe cell lumen. The perforation of the endwall OCCUR while the tonoplast is still intact. Theplasmalemmasof the contiguous cells withdraw from the part of the wall undergoingdegradation. The space becomes filled with fibrous debris ofthe apparently lysed wall. The degraded wallpart becomes brokenpossibly by a unidirectional pressure flow in the cells, forthe remnants of the wall are pushed into one of the two superimposedcells. At this presumably mature stage, the cells contain someintactprotoplast components among which ribosomes are especially conspicuous.     

Anatomy of the Secondary Phloem and the Crystalliferous Phloem Fibers in the Stem of Torreya grandis

The structure of the secondary phloem and the development of the crystaleiferous phloem fibers in the stem of Torrey grandis were observed under the ligth microscope and SEM. The secondary phloem is composed of sieve cells, phloem parenchyma cells, crystalliferous phloem fibers and stone cells in the longitudinal system, and the uniserite homogeneous phloem rays consisting of parenchyma cells only in the radial system. In the cross section, there are 3–9 sieve cells in radial rows forming discontinuous tangential layers, the crystalliferous phloem fibers often in a single discontinuous tangential layer and the stone cells dispersed in rangential layer of phloem parenchyma. The developmental process of crystalliferous phloem fibers is as follows: initial cells appeared in the end of April and were well differentiated in the first week of May. Some crystals were deposited in the primary wall, while others were free in the cell. At the end of May, the secondary wall of most crysalliferous phloem fibers started to be thickened. With the thickening of the secondary wall, all the crystals were embedded in the wall from June to August From the end of September to the early days of October, the crystalliferous phloem fibers reached their full maturation. It is shown by microchemical identification and EDAX analysis that the crystals embedded in the wail of crystalliferous phloem fibers are calcium oxalate crystals.