毛竹茎秆纤维细胞发育过程中ATP酶的超微细胞化学定位研究

采用磷酸铅沉淀技术,对毛竹茎秆纤维细胞发育过程中的ATP酶进行了超微细胞化学定位研究.在初生壁形成时期,大量的ATP酶的活性产物沉积在质膜、质膜内陷、运输小泡、胞间连丝等膜体系以及细胞核和各种细胞器上;在次生壁形成的初期,ATP酶在多泡小体和裂解的液泡膜上出现,凝聚并边缘化的染色质上仍然具有ATP酶活性;随着次生壁的逐渐加厚,在前四年中持续存在具有ATP酶活性的质膜内陷结构,以后消失;而在六年生纤维细胞的质膜、运输小泡、纹孔、胞间连丝和凝聚化的染色质上仍然发现有明显的ATP酶分布,并发现在染色质上ATP酶活性会随着凝聚程度的加深而增强.结果表明,ATP酶在毛竹茎秆纤维细胞壁的整个形成过程中发挥重要作用,而纤维细胞的次生壁形成过程是一个由核基因控制的主动的PCD过程;并证实毛竹茎秆纤维细胞的发育有别于其它木本植物纤维细胞的发育过程,这种纤维细胞是一种典型的长寿细胞.     

杂交鹅掌楸体胚发生过程中ATP酶活性的超微细胞化学定位

利用透射式电镜,通过胚性细胞的超微切片观察,对杂交鹅掌楸体细胞胚胎发生和发育过程中ATP酶活性进行了超微细胞化学定位.结果表明,非胚性细胞的质膜、液泡膜等膜系统当中存在ATP酶活性,质体、核膜、细胞壁以及细胞间隙上有少许沉积;早期胚性细胞ATP酶反应产物主要沉积于质膜、液泡膜上、淀粉粒、细胞壁加厚处;胚性细胞后期ATP酶活性从质膜逐渐转移入细胞内,细胞质、壁旁体、胞间连丝、细胞膜与细胞间隙、细胞核等处均有ATP酶活性反应.随着胚性细胞的发育及分裂,包裹细胞的厚壁、细胞核、核仁与染色质等处也出现ATP酶活性反应沉淀物.说明杂交鹅掌楸体细胞胚胎发生及发育过程中存在丰富的能量代谢.     

小麦与条锈菌互作中过氧化物酶的细胞化学研究

采用细胞化学方法对小麦与条锈菌互作过程中过氧化物酶的分布及其活性大小进行了研究,结果表明：过氧化物酶主要分布于细胞壁和细胞间隙中;在未行接种的小麦叶片中,抗病品种和感病品种的过氧化物酶活性均比较低;条锈菌侵染后,诱导抗、感病品种叶片中的过氧化物酶活性升高,且抗病品种升高的幅度明显大于感病品种;感病品种中过氧化物酶活性在侵染位点附近细胞壁上表现升高,而抗病品种中该酶的活性在侵染点细胞以及远离侵染点的叶肉细胞的细胞壁和细胞间隙中均显著升高。高活性的过氧化物酶是小麦抗条锈性的生化标记和重要机制之一。     

一种特殊的长寿细胞:毛竹茎秆纤维细胞

利用显微和细胞化学方法,对毛竹(Phyllostachys edulis)茎秆纤维次生壁形成过程中超微结构变化以及ATP酶、Ca2 -ATPase和酸性磷酸酶的超微细胞化学定位进行了研究.研究发现,次生壁形成早期,细胞核具有双层核膜,染色质凝聚,可见大量的线粒体、粗面内质网和高尔基体等细胞器存在于纤维细胞中;随后,双层核膜消失,细胞器将逐渐解体,多泡体开始出现在纤维细胞的细胞质;随着年龄的增加,纤维细胞壁逐渐增厚,并出现多层结构现象,而运输小泡、细胞膜、胞间连丝和凝聚的染色质将持续存在.在次生壁形成的整个过程中,ATP酶、Ca2 -ATPase和酸性磷酸酶在运输小泡、细胞膜、质膜内陷、胞间连丝和凝聚的染色质中将持续存在.结果表明,毛竹茎秆纤维细胞是一种不同于木本双子叶植物的长寿细胞,纤维原生质体中ATP酶和酸性磷酸酶的持续存在与次生壁的持续增厚密切相关.     

一种特殊的长寿细胞: 毛竹茎秆纤维细胞

利用显微和细胞化学方法, 对毛竹( Phyllostachys edulis) 茎秆纤维次生壁形成过程中超微结构变化以及ATP 酶、Ca²⁺ -ATP_ase 和酸性磷酸酶的超微细胞化学定位进行了研究。研究发现, 次生壁形成早期,细胞核具有双层核膜, 染色质凝聚, 可见大量的线粒体、粗面内质网和高尔基体等细胞器存在于纤维细胞中; 随后, 双层核膜消失, 细胞器将逐渐解体, 多泡体开始出现在纤维细胞的细胞质; 随着年龄的增加,纤维细胞壁逐渐增厚, 并出现多层结构现象, 而运输小泡、细胞膜、胞间连丝和凝聚的染色质将持续存在。在次生壁形成的整个过程中, ATP 酶、Ca²⁺ -ATP_ase 和酸性磷酸酶在运输小泡、细胞膜、质膜内陷、胞间连丝和凝聚的染色质中将持续存在。结果表明, 毛竹茎秆纤维细胞是一种不同于木本双子叶植物的长寿细胞, 纤维原生质体中ATP 酶和酸性磷酸酶的持续存在与次生壁的持续增厚密切相关。     

番茄子叶细胞内三磷酸腺苷酶活性的超微结构定位及其在冷害中的变化

采用磷酸铅沉淀的细胞化学方法,对番茄子叶细胞内三磷酸腺苷酶(ATPase)活性进行了超微结构的定位,并研究了番茄幼苗在遭受冷害过程中 ATPase 活性的变化。结果指出:1.在28℃下萌发生长的番茄幼苗子叶细胞内的 ATPase 活性被定位于质膜、胞间连丝、核仁及核的染色质、叶绿体片层膜、部分细胞壁以及细胞间隙周围的细胞壁表面及其内含物上。2.当番茄幼苗遭受12小时冷(5℃)处理时,质膜、细胞壁及细胞间隙内的 ATPase 活性开始明显地降低,但细胞核和叶绿体片层膜上的 ATPase 仍保持高的活性反应。在冷处理24小时后,质膜与细胞壁的 ATPase 活性几乎完全丧失,而细胞核和叶绿体片层膜的 ATPase 活性仅开始减弱。这种情况揭示,冷害可能首先损伤细胞表面(质膜与壁)的 ATPase 活性。3.讨论了细胞间隙作为养料运输通道的作用以及冷害的一种可能过程与机理。关于高等植物细胞内三磷酸腺苷酶(ATPase)活性的细胞化学的超微结构定位,以往主要集中于维管束的韧皮部和根尖细胞的研究。不久前,我们报道了冬小麦分蘖节细胞内 ATPase 活性的细胞化学定位叫,初步揭示 ATPase 的活性变化与植物抗寒性有密切关系。番茄等喜温植物在冷害中的细胞超微结构,呼吸作用和一些酶(如过氧化物酶,过氧化氢酶及吲(口朶)乙酸氧化酶)活性的变化,已有一些报道,提出膜可能是冷害损伤的最初部位。然而冷害究竟首先是损伤膜的拟脂成分,还是损伤膜的蛋白质成分,或者是二者同时遭到破坏,目前的实验证据还十分缺乏。ATPase 是膜束缚的一种功能性蛋白质,我们试图通过探索它在寒害中的活性变化,为阐明寒害机理提供实验依据。     

杜仲次生木质部分化过程中木质素与半纤维素组分在细胞壁中分布的动态变化

利用紫外光显微镜、透射电子显微镜结合免疫胶体金标记,研究了杜仲（Eucommia ulmoides Oliv.)次生木质部分化过程中木质素与半纤维素组分（木葡聚糖和木聚糖）在细胞壁分布的动态变化。在形成层及细胞伸展区域,细胞壁具有木葡聚糖的分布,而没有木聚糖和木质素沉积,随着次生壁S1层的形成,木质素出现在细胞角隅和胞间层,木聚糖开始出现在S1层中,此时木葡聚糖则分布在初生壁和胞间层;随着次生,壁S2层及S3层的形成和加厚,木质逐逐步由细胞角隅和胞间层扩展到S1、S2和S3层,其沉积呈现出不均匀的块状或片状沉积模式,在次生壁各层形成与其木质化的同时,木聚糖逐渐分布于整个次生壁中,而木糖聚糖仍局限分布于初生壁和胞间层。结果表明,随着细胞次生壁的形成与木质化,细胞壁结构发生较大变化。细胞壁的不同区域,如细胞角隅、胞间层、初生壁和次生壁各层,具有不同的半纤维素组成,其与木质等细胞壁组分结构构成不同的细胞壁分子结构。     

厚壁毛竹快速高生长期竹秆ATP酶超微细胞化学定位

采用电镜细胞化学技术对厚壁毛竹(Phyllostachys edulis ‘Pachyloen’)快速高生长期竹秆节间的伸长发育过程（包括：分生细胞期、伸长初期、快速伸长期和成熟期四个阶段）进行ATP酶超微细胞化学定位,以揭示竹秆节间快速伸长的细胞学基础。结果表明：分生细胞期,细胞质膜、核膜、细胞器膜系统上等均有很强的ATP酶活性。伸长初期,节间上部基本组织细胞质膜上ATP酶活性较强,且短细胞质膜上的ATP酶活性更强,节间基部各细胞均未观察到ATP酶活性。快速伸长期,节间基部基本组织ATP酶活性较节间上部高,细胞质膜、运输小泡膜、胞间隙及胞间连丝上均有ATP酶活性。成熟期,仅节间上部基本组织质膜上有较弱的ATP酶活性。ATP酶在节间伸长过程中主要参与新细胞壁物质的分泌和共质体运输,促进新细胞壁的形成,晶体和淀粉粒体外膜上ATP酶活性的存在表明其具有贮存物质的作用。节隔缺失节的节间基部未观察到ATP酶活性,节部韧皮结细胞ATP酶活性较高,节隔的缺失引起节部与节间与物质运输有关结构的变化,进而影响节间伸长生长。     

毛竹茎秆纤维细胞发育过程中的细胞程序性死亡

利用TUNEL检测、细胞学及细胞化学方法,对毛竹茎秆纤维细胞发育过程中的细胞程序性死亡进行了研究。在次生壁形成的早期,纤维细胞出现染色质凝聚、细胞器膨胀、液泡膜解体和细胞质泡状化等典型的细胞程序性死亡形态学特征;TUNEL检测反应呈阳性,显示此时的纤维细胞核DNA发生了片段化。此时,在纤维细胞裂解的液泡膜、降解的细胞质和凝聚的染色质上具有ATPase活性。纤维细胞质的Ca^2＋水平会随着次生壁的形成而逐渐升高,随后Ca^2＋聚集成块状。在初生壁形成后期,纤维细胞染色质上的酸性磷酸酶（APase）活性增强。随着纤维次生壁的持续增厚,ATPase、酸性磷酸酶和Ca^2＋将在裂解的细胞质和凝聚的染色质上持续存在多年。结果表明,毛竹茎秆纤维细胞的次生壁形成过程是一个主动自溶的细胞程序性死亡过程。初生壁形成后期染色质上酸性磷酸酶活性增强及次生壁形成期胞质Ca^2＋的聚集,与纤维细胞的程序性死亡密切相关。ATPase,Ca^2＋和APase参与了纤维细胞程序性死亡过程中原生质体的降解。     

拟南芥叶片细胞包被系统酸性降解的光镜观察

观察了拟南芥叶片细胞包括细胞壁和质膜在内的细胞包被系统在酸性条件下酶促降解的过程。观察发现,处于酸性酶解液中的拟南芥叶片,最初细胞壁完整,细胞排列有序,其后细胞壁开始部分降解,细胞排列逐渐进入无序状态,随后细胞壁完全降解,去壁的原生质体完全进入游离状态,游离原生质体的质膜也随之降解,细胞器溢出后以细胞核为核心积聚、重组为新的原生质体。进一步观察了这一过程中细胞pH值的改变,结果发现,酸性酶解过程中细胞倾向于pH值降低,而细胞器重组产生的新原生质体pH值向正常水平恢复。因此,酸性环境对拟南芥叶片细胞包被系统的降解产生重要的影响。     

毛竹茎细胞壁半纤维素多糖的免疫细胞化学定位研究

本文以毛竹(Phyllostachys pubescens)为材料,采用免疫细胞化学标记方法对两种细胞壁半纤维素多糖成分,即木聚糖(Xylan)和(1-3)(1-4)-β-葡聚糖［(1-3)(1-4)-β-glucan］在毛竹茎中的分布进行了观察。结果表明,应用免疫细胞化学方法可以准确、有效地观察这两种半纤维素多糖成分在细胞壁中的分布;木聚糖分布在已木质化的组织细胞的细胞壁中,与细胞壁木质化有密切关系;(1-3)(1-4)-β-葡聚糖在幼竹茎基本组织中分布于短薄壁细胞细胞壁中及长薄壁细胞胞间层,而在老龄竹茎基本组织中,仅分布于短薄壁细胞细胞壁中,而长薄壁细胞细胞壁却无此成分,反映出长、短薄壁细胞细胞壁组成上的差异。     

Toward understanding the different function of two types of parenchyma cells in bamboo culms

The bamboo, woody monocot, has two types of parenchyma cells in the ground tissues of its culm, in contrast to a single type of parenchyma cell in rice, maize and other major crop species. The distribution of cell wall components, including lignin, (1-->3), (1-->4)-beta-D-glucans (MGs), the highly-substituted glucuronoarabinoxylans (hsGAXs) and low-branched xylans (lbXs) in ground parenchyma tissue of Phyllostachys heterocycla var. pubescens culms was studied at various developmental stages using light microscopy (LM), UV-microscopy, transmission electron microscopy (TEM) and immunolabeling techniques. The short parenchyma cell walls were lignified in 2-month-old bamboo culms just as the long parenchyma cell walls were. The lignified regions were confined to the portions in contact with the long parenchyma cell walls, while the walls at the cell corner region never lignified, even in 7-year-old culms. Significant differences were also found in the hemicellulose distribution between the short and long parenchyma cell walls. In bamboo parenchyma tissue, MGs were localized in short parenchyma cell walls and few were found in long parenchyma cell walls in both young and 7-year-old culms. The distribution of hsGAXs was similar to that of MGs in young culms, but they only appeared in the cell corner region of short parenchyma cells in old culms. Low-branched xylans were distributed in the lignified, but not in unlignified parenchyma cell walls. Based on this evidence, the differences of function in both short and long parenchyma cells in a bamboo culm are discussed.     

Ultrastructure of fibre and parenchyma cell walls during early stages of culm development in Dendrocalamus asper

BACKGROUND AND AIMS: The anatomy of bamboo culms and the multilayered structure of fibre cell walls are known to be the main determinant factors for its physical and mechanical properties. Studies on the bamboo cell wall have focussed mainly on fully elongated and mature fibres. The main aim of this study was to describe the ultrastructure of primary and secondary cell walls in culm tissues of Dendrocalamus asper at different stages of development. METHODS: The development of fibre and parenchyma tissues was classified into four stages based on light microscopy observations made in tissues from juvenile plants. The stages were used as a basis for transmission electron microscopy study on the ultrastructure of the cell wall during the process of primary and early secondary cell wall formation. Macerations and phloroglucinol-HCl staining were employed to investigate fibre cell elongation and fibre cell wall lignification, respectively. KEY RESULTS: The observations indicated that the primary wall is formed by the deposition of two distinct layers during the elongation of the internode and that secondary wall synthesis may begin before the complete cessation of internode and fibre elongation. Elongation was followed by a maturation phase characterized by the deposition of multiple secondary wall layers, which varied in number according to the cell type, location in the culm tissue and stage of shoot development. Lignification of fibre cell walls started at the period prior to the cessation of internode elongation. CONCLUSIONS: The structure of the primary cell wall was comprised of two layers. The fibre secondary cell wall began to be laid down while the cells were still undergoing some elongation, suggesting that it may act to cause the slow-down and eventual cessation of cell elongation.     

Immunohistochemical localization of hemicelluloses and pectins varies during tissue development in the bamboo culm

The distribution of hemicelluloses and pectins in bamboo internodes was studied immunocytochemistrically at various stages of development. The ultra-structures of bamboo cell walls have been reported previously at various stages. The internodes were identically classified into three developmental phases: primary wall stage (phase I), unlignified secondary wall stage (phase II) and lignified wall stage (phase III), using the same bamboo culm. (1-->3, 1-->4)-Beta-glucans were distributed in nearly all tissues in an actively elongating stage. Limited amounts of beta-glucans were deposited in primary walls and the middle lamellae, but were limited to the phloem in secondary walls. This suggests that the function of beta-glucans might be different in phloem vis-à-vis other tissues. Highly-substituted xylans were located in nearly all tissues of early phase I, but had disappeared in all tissues immediately prior to lignification. In contrast, low-branched xylan epitopes were present only in the protoxylem in phase I, but were present in all tissues immediately prior to lignification in phase II. In phase III, the epitopes were densely localized in lignified walls, suggesting that the substitution of xylans is closely related to maturation. Methyl-esterified (but not unesterified) pectins were present in all tissues of early phase I. Just before and after lignification, both types of pectins were concentrated in the phloem and protoxylem. Xyloglucans were largely distributed in the phloem and in lignified tissues, suggesting that they might be closely correlated with maturation. This represents the first account of the distribution of hemicelluloses and pectins at the tissue and ultrastructural level in bamboo internodes at various stages of development.     

Immunohistochemical Localization of Hemicelluloses and Pectins Varies During Tissue Development in the Bamboo Culm

The distribution of hemicelluloses and pectins in bamboo internodes was studied immunocytochemistrically at various stages of development. The ultra-structures of bamboo cell walls have been reported previously at various stages. The internodes were identically classified into three developmental phases: primary wall stage (phase I), unlignified secondary wall stage (phase II) and lignified wall stage (phase III), using the same bamboo culm. (1→,1→4)-β-Glucans were distributed in nearly all tissues in an actively elongating stage. Limited amounts of β-glucans were deposited in primary walls and the middle lamellae, but were limited to the phloem in secondary walls. This suggests that the function of β-glucans might be different in phloem vis-à-vis other tissues. Highly-substituted xylans were located in nearly all tissues of early phase I, but had disappeared in all tissues immediately prior to lignification. In contrast, low-branched xylan epitopes were present only in the protoxylem in phase I, but were present in all tissues immediately prior to lignification in phase II. In phase III, the epitopes were densely localized in lignified walls, suggesting that the substitution of xylans is closely related to maturation. Methyl-esterified (but not unesterified) pectins were present in all tissues of early phase I. Just before and after lignification, both types of pectins were concentrated in the phloem and protoxylem. Xyloglucans were largely distributed in the phloem and in lignified tissues, suggesting that they might be closely correlated with maturation. This represents the first account of the distribution of hemicelluloses and pectins at the tissue and ultrastructural level in bamboo internodes at various stages of development.     

Intercellular pectic protuberances in Asplenium: new data on their composition and origin

BACKGROUND AND AIMS: Projections of cell wall material into the intercellular spaces between parenchymatic cells have been observed since the mid-19th century. Histochemical staining suggested that these intercellular protuberances are probably pectic in nature, but uncertainties about their origin, composition and biological function(s) have remained. METHODS: Using electron and light microscopy, including immunohistochemical methods, the structure and the presence of some major cell wall macromolecules in the intercellular pectic protuberances (IPPs) of the cortical parenchyma have been studied in a specimen of the Asplenium aethiopicum complex. KEY RESULTS: IPPs contained pectic homogalacturonan, but no evidence for pectic rhamnogalacturonan-I or xylogalacturonan epitopes was obtained. Arabinogalactan-proteins and xylan were not detected in cell walls, middle lamellae or IPPs of the cortical parenchyma, whereas xyloglucan was only found in its cell walls. Extensin (hydroxyproline-rich glycoproteins) LM1 and JIM11 and JIM20 epitopes were detected specifically in IPPs but not in their adjacent cell walls or middle lamellae. CONCLUSIONS: It is postulated that IPPs do not originate exclusively from the middle lamellae because extensins were only found in IPPs and not in surrounding cell walls, intercellular space linings or middle lamellae, and because IPPs and their adjacent cell walls are discontinuous.     

Regulation of assimilation and senescence by the fruit in monocarpic plants

Intercellular acidic isoperoxidases (EC 1.11.1.7) isolated from exponentially growing lupin ( Lupinus albus . L. cv. multolupa) hypocotyls are under the control of exogenously applied auxins. Application of auxins leads to a short-term reduction in the level of free intercellular peroxidases, and this effect is associated with a binding of these free peroxidases to the cell walls, probably mediated by an acidification of the cell wall. The ratio of free intercellular peroxidases to the total intercellular peroxidase activity, varies along the axis of exponentially growing hypocotyls. It has a V-shaped distribution with the minimum value in the elongation III-zone, where high levels of auxins have previously been implied in differentiation. This minimum value coincides spatially with the first signs of cell wall thickening in the hypocotyl cells and, paradoxically, it is out of phase with respect to the maximal cell elongation. On the other hand, the ratio of free intercellular peroxidases reaches its maximal values in both the most undiffercntiated phloem cells and the differentiated xylem cells. High levels of free intercellular peroxidase activity in phloem cells are hard to explain, since phloem cell walls remain unlignified during almost all stages of differentiation. However, association of free intercellular peroxidase activity with xylem cells is clearly associated with the lignification of the xylem cell walls. The physiological significance of the binding vs release of intercellular peroxidase is discussed in relation to the catalytic properties and stability at acidic pH of both the bound and free forms of this enzyme.     

毛竹地下茎对创伤的反应

研究了在中国最为广泛栽培的毛竹(Phyllostachys edulis(Cart.)H.de Lehaie)的地下茎的创伤反应。创伤后的第1天,在伤口附近没有明显反应;2d之后,创口附近可以观察到生理反应的代谢物,在后生木质部的导管中以及在基本组织细胞的胞间隙出现粘状物质,这些粘状物质具有果胶特性;创伤后1周,创口附近的筛管及基本组织中的短细胞的细胞壁变成木质化。同时,基本组织中的长细胞的内壁出现新的次生壁的沉积;2周后,创伤反应的组织与未受创伤的组织之间的区别变得更加明显;4周后,一些导管完全充满了粘性物质,但没有观察到侵填体。由于细胞壁的木质化及酚类物质的填充,筛管完全失去了功能。对创伤后6周的材料进行观察的结果表明,其创伤反应的范围不再扩展,在创伤组织与未受伤组织之间的基本组织的细胞壁变得相当厚,从而在两者之间形成一道屏障。毛竹地下茎的这种创伤反应与毛竹竹竿的创伤反应基本上是一致的,只是略有不同。     

Cortical development in roots of the aquatic plant Pontederia cordata (Pontederiaceae)

Adventitious roots of marsh-grown Pontederia cordata were examined to determine cortical development and structure. The innermost layer of the ground meristem forms the endodermis and aerenchymatous cortex. The outermost layer of the early ground meristem undergoes a precise pattern of oblique and periclinal cell divisions to produce a single or double layer of prohypodermis with an anchor cell for each radial file of aerenchyma cells. At maturity, endodermal cell walls are modified only by narrow Casparian bands. The central regions of the ground meristem become proaerenchyma and exhibit asymmetric cell division and expansion. They produce an aerenchymatous zone with barrel-shaped large cells and irregularly shaped small cells traversing the aerenchyma horizontally along radii; some crystalliferous cells with raphides are present in the aerenchyma. The walls of the hypodermis are modified early by polyphenols. The outermost layer of the hypodermis later matures into an exodermis with Casparian bands that are impermeable to berberine, an apoplastic tracer dye. The nonexodermal layer(s) of the hypodermis has suberin-modified walls. Radial files of aerenchyma are usually connected by narrow protuberances near their midpoints, the aerenchyma lacunae having been produced by expansion of cells along walls lining intercellular spaces. We are terming this type of aerenchyma development, which is neither schizogenous nor lysigenous, "differential expansion."     

The Anatomical Structure of Culms of Phyllostachys pubescens Mazel ex H. de Lehaie

A culm consists of the rind, basic and vascular systems. The rind system is composed of epidermis, hypodermis and cortex which are of small, thick-walled and well packed cells and mainly functions as an outer wall to protect the culm tissues. The basic system is made up of ground tissue and pith-ring. Pith-ring is the inner wall of the culm consisting of several layers of densely arranged, highly lignified cells. Between the rind system and pith-ring is the ground tissue in which collateral vascular bundles are well embedded. Vascular bund]es are well developed with four fibre caps, two lateral on either side of vessels and two polar, one outside the phloem and the other around the intercellular space. All of them function effectively in fixing the conductive elements in position and strengthening the ground tissue around within the culm wall. Vessels and sieve tubes are of vital importance to bamboo life, but partially blocked and eventually lose their conductivity due to deposition of tylosis that may cause death of the aged culms. All cells are strictly axially arranged within the internodes of culm, but become highly modified in the nodes. During intercalary growth of bamboo shoot the vascular bundles of a sheath are connected with those of the culm periphery and become abscissed off to form a sheath scar around the node after cessation of the growth. Inside the periphery, vascular bundles are variably crooked, branched or reunited in the node which becomes causatively swollen, especially in the joint of side branches. Some nodal bundles bend radially inward to pass into the diaphragm where they are irregularly interwoven within the ground tissue, play an important role in transverse conduction and provide mechanical support of the culm.