Characteristics of liver regeneration after vagotomy

Peculiarities of a reparative process in the hepatic parenchyma have been studied after toxic effect of CCl4, at vagotomy in 1, 2 and 4 weeks after the operation. Appearance of a more massive lesion and decreasing regeneration of the vagotomized liver have been revealed. The proliferative activity of hepatocytes, normal and after vagotomy has a principally similar character and is described as a curve with two picks, having its maximum on the 2nd and the 5th-6th days after xenobiotic administration. The intensity of the hepatocyte proliferative activity in the denervated liver essentially surpasses that in the control and decreases, as the area of the parenchymal lesion decreases in the latest time after the operation.     

Histochemical studies of noradrenergic innervation of the liver in untreated and daunomycin-pretreated guinea-pigs

Summary The pattern of noradrenergic innervation of guinea-pig hepatic tissue was examined by using the fluorescence method of Falk et al. (1962). The distribution of monoaminergic nerve fibres in untreated animals was clearly evident at the level of the portal vein, the hepatic artery and the bile duct. The hepatic artery was the most densely innervated. Mast cells and Kupffer cells had no connection with the adrenergic fibres. In daunomycin-pretreated animals, the hepatic cells appeared to be deep red in colour owing to the presence of the antibiotic. Some noradrenergic nervous fibres, never previously described, were unexpectedly distinguishable in the liver parenchyma against the background red colour of daunomycin-pretreated tissue. They appeared to be contiguous to the hepatocytes and were of different shapes: comma-like, V-like, or like a string of pearls. The nature and the functional role of these elements is briefly discussed.     

WOOD ANATOMY OF TREMANDRACEAE: PHYLOGENETIC AND ECOLOGICAL IMPLICATIONS

Stems of four species of the Australian family Tremandraceae furnished sufficient material for analysis of wood anatomy. Presence of simple perforation plates on vessel elements, occurrence of libriform fibers (some septate), tendency toward vasicentric parenchyma, presence of crystalliferous axial parenchyma strands, presence of crystals singly in ray cells, and occurrence of amorphous deposits in parenchyma are all features in which Tremandraceae resemble Pittosporaceae. Wood anatomy tends to support a “rosoid” rather than a sapindalean, rutalean, or polygalalean affinity for Tremandraceae, although wood is only a preliminary indicator. By the use of numerical indices as well as such indicators as helical thickening and presence of vascular tracheids, wood of Tremandraceae is shown to be highly xeromorphic. The genus Tremandra may represent a secondary entrant into wet forests of southwestern Australia; it clearly is not relict from mesic ancestry.     

石蒜属12 种植物叶片比较解剖学研究

 对石蒜属( Lycoris Herb. ) 12 种植物叶片的比较解剖学研究表明: (1) 石蒜属植物叶片横切面的端部、中部及基部的轮廓基本呈浅“W”或“V”字型, 有些种的表皮细胞上具有明显的尖刺状乳突; ( 2)石蒜属植物均为异面叶, 叶肉组织有一定的栅栏组织和海绵组织分化, 但二者的厚度、叶肉中所占比例及栅栏组织的细胞层数在种间有一定的差异; (3) 海绵组织发达、具有大而明显的薄壁细胞或细胞裂溶后形成空腔(分泌腔或气腔); (4) 叶片中维管束数目大多为奇数, 叶脉维管束鞘由薄壁细胞组成; (5) 石蒜属植物横切面上叶缘的形状分为圆弧形和楔形两种类型。石蒜属植物叶的解剖结构具有许多相似特征; 同时又具有一定的种间差异, 可为石蒜属植物的种间关系和开发利用提供有价值的信息。     

The role of HGF on invasive properties and repopulation potential of human fetal hepatic progenitor cells

The success of hepatocyte transplantation has been limited by the low efficiency of transplanted cell integration into liver parenchyma. Human fetal hepatic progenitor cells (hepatoblasts) engraft more effectively than adult hepatocytes in mouse livers. However, the signals required for their integration are not yet fully understood. We investigated the role of HGF on the migration and invasive ability of human hepatic progenitors in vitro and in vivo.Hepatoblasts were isolated from the livers of human fetuses between 10 and 12 weeks of gestation. Their invasive ability was assessed in the presence or absence of HGF. These cells were also transplanted into immunodeficient mice and analyzed by immunohistochemistry.In contrast to TNF-alpha, HGF increased the motogenesis and invasiveness of hepatoblasts, but not of human adult hepatocytes, via phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. The invasive ability of human hepatoblasts correlated with the expression and secretion of matrix metalloproteinases (MMPs). Hepatoblasts stimulated with HGF prior transplantation into newborn mice migrated from the portal area into the hepatic parenchyma.Conclusions: In contrast to adult hepatocytes, hepatoblasts display invasive ability that can be modulated by HGF in vitro and in vivo.     

杨树叶薄层培养中不定芽形态发生的细胞组织学研究

将杂种杨树(Populus nigra var.betulifolia×P.trichocarpe)NE299叶主脉用振动切片机横切成400μm或800μm的薄切片,培养在附加0.2mg/L BA和0.01mg/L NAA的木本植物培养基上。培养后,位于主脉维管束两侧中上部的维管束鞘薄壁细胞首先启动分裂。几乎同时,与其邻接的一些栅栏组织细胞也分裂,并很快形成胚性分生细胞团。主脉的愈伤组织主要由维管束鞘薄壁细胞,以及与其邻接的一些栅栏组织细胞和韧皮部的薄壁细胞分裂而来。不定芽通常发生在愈伤组织的周边区,也可以起源于维管组织结节(vascular nodules)周围的形成层状细胞。侧脉的维管束鞘细胞分裂活动很强,可不经愈伤组织直接长成不定芽。杨树叶主脉处的维管束鞘薄壁细胞在与叶肉组织相邻接的细胞中,通常含有少量较小的叶绿体,而位于背腹面的细胞中含有贮藏的淀粉。对形态发生的特定部位及其细胞进行了讨论。     

Liver architecture.

The development of liver parenchyma starts from entodermal cells which grow out from the gut into the mesenchyma of the septum transversum. In the definitive organ this close association of epithelial cells (hepatocytes) and mesenchyma-derived nonparenchymal cells is maintained. The liver, and with it each hepatocyte, acts in two directions: the vascular poles of the hepatocytes serve in an ingestive sense, while at their biliary poles secretory functions are exerted. Hepatic microvascularization comprises two afferent vessels (arterial and portal terminal branches), the sinusoids and the terminal hepatic venule. Sinusoidal cells surround the capillaries but also have highly specialized functions with regard to filtration, phagocytosis, fat storage and defense. The autonomic innervation plays an important role in the regulation of metabolic functions. Above the cellular level the proper architecture of the liver parenchyma has been the object of controversial discussions for centuries. The concept of the liver lobule, the portal unit, the liver acinus and other structures are presented and discussed. Finally, the liver parenchyma is described as an irregular interdigitating system of regions related to the terminal blood vessels.     

八角莲组织培养的器官发生途径研究

为探究小檗科植物八角莲组织培养的器官发生方式,该研究以八角莲离体叶片、叶柄在MS培养基上诱导产生的愈伤组织、不定芽、不定根为对象,用连续石蜡切片技术分析八角莲组织培养的器官发生途径。结果表明:八角莲愈伤组织形成的解剖学特征是靠近表皮的薄壁细胞经激素刺激恢复分裂能力,继续培养形成拟分生组织。拟分生组织可形成许多分化中心。通过对八角莲组织培养产生的不定芽细胞组织学观察发现芽原基起源于愈伤组织外侧的几层薄壁细胞,芽原基背离愈伤组织中央生长形成不定芽,故八角莲脱分化形成的芽起源方式为外起源。而八角莲的根原基起源于组织深处髓部薄壁细胞和部分维管形成层细胞,进而形成类似球形或楔形并朝韧皮部突起的根原基轮廓,根原基继续发育会突破表皮生成不定根,起源方式为内起源。八角莲离体再生途径为器官发生型,在组培苗生长过程中先诱导形成不定芽,再诱导形成不定根,在愈伤组织上形成维管组织将不定芽和不定根连接成完整植株。     

Vegetative anatomy of subtribe Habenariinae (Orchidaceae)

Leaves of Habenariinae are characterized by anomocytic stomatal apparatuses, homogeneous mesophyll, collateral vascular bundles in a single series, and thin-walled bundle sheath cells. There is no foliar sclerenchyma nor a hypodermis. Cauline cortex consists of thin-walled living cells among which are large and numerous intercellular spaces. The ground tissue is bordered externally by a layer of thick-walled living cells, except in Habenaria repens. Central ground tissue cells are living, and usually thin-walled surrounding intercellular spaces of various dimensions. These are conspicuously large in H. repens. Collateral vascular bundles are scattered across the ground tissue. Sclerenchyma is absent. Absorbing roots are generally velamentous, exodermal dead cells are diin-walled, and passage cells usually have a thickened outer wall. A regular vascular cylinder is present, and vascular tissue is embedded in parenchyma. Root tubers are velamentous, exodermal cells are usually thin-walled, and passage cells frequently have thickened outer walls. Vascular tissue of root tubers is organized into two classes: (1) those with a single vascular cylinder surrounded by a cortex and (2) those with a series of meristeles dispersed throughout the ground tissue. In group (1) cortex is homogeneous either with or without mucilage cells except in Stenoglattis where the cortex is heterogeneous, consisting of water-storage and assimilatory cells, and lacks mucilage cells. In group (2) the ground tissue consists of larger mucilage-containing cells and smaller assimilatory cells.     

Hepatocyte transplantation in a model of toxin-induced liver disease: variable therapeutic effect during replacement of damaged parenchyma by donor cells

To provide long-term therapy in patients with severe toxin-induced hepatic parenchymal damage, donor hepatocytes would need to replicate and replace a large portion of the damaged parenchyma. Using a mouse model developed to reproduce this type of hepatic injury, we found that hepatocyte transplantation only slightly improved survival after transplantation despite the fact that many non-survivors showed moderate liver repopulation by donor cells. Perhaps accounting for this outcome, donor parenchyma in non-survivors did not have typical lobular organization. These results indicate that the re-creation of functional parenchyma by transplanted hepatocytes requires time, during which donor cells proliferate and then establish normal parenchymal architecture.     

A study of the source of virus in the Pholem exudate appearing on leaves of Amscinckia infected with the beet curly top virus

Abstract Leaves of Amsinckia douglasiana discharging phloem exudate after infection with the beet curly top virus (BCTV) were studied with the electron microscope. Infected tissue differed from the noninfected in having much hyperplastic phloem characterized by abnormally high proportion of sieve elements, scarcity of companion cells, degenerating parenchyma cells, and some unusually large intercellular spaces. Many spaces contained amorphous debris. Particles resembling BCTV were discernible within the debris. Such particles were encountered also in the debris trapped between stomatal guard cells. Since the phloem exudate excreted from leaves of BCTV-infected plants contains virus particles, and since the virus is found extremely rarely in sieve elements, we suggest (1) that most of BCTV particles apparently released into intercellular spaces are derived from degenerating parenchyma cells in which the virus had multiplied; (2) that the exudate is derived from sieve elements of the hyper-plastic phloem in which the normal functional control by companion cells is lacking; (3) that the exudate leaks from the nontransporting sieve elements through cell walls into intercellular spaces and carries the virus to the outside. Initially, stomata may serve as exits for the infectious exudate, but subsequently ruptures in the epidermis are involved.     

Liver epithelioid progenitor cells derived from fetal Luxi bovine alleviate liver fibrosis

Liver epithelioid progenitor cells (LEPCs) have important roles in liver therapy because of their hepatic differentiation potency in vitro and in vivo. Despite many researches on humans, mice, and rats, equivalent progenitor cells derived from bovine are relatively rare. The purpose of our current study is to characterize bovine LEPCs, and research on the cure potency of this heteroplastic progenitor cells on mice liver fibrosis. We have used collagenase IV digesting and differential adhesion method to isolate slabstone shape, EpCAM, LGR5, NCAM1 and SOX9 positive progenitor cells from fetal Luxi bovine liver. When cultured in hepatic differentiation media containing 20 ng/ml Oncostatin M, LEPCs can differentiate into hepatocytes in vitro. After 4 weeks of intravenous tail vein injection into CCl₄-injured mouse liver, LEPCs engrafted into liver parenchyma, differentiated into ALB positive hepatocytes, and could alleviate liver fibrosis through down regulating fibrosis genes-Tgfb1 and α-SMA as well as decreasing expression of collagen gene Col1a1, Col3a1, and Col4a1, and regain liver function by recovering ALT and AST. Our findings provided a useful tool for studying liver development in vitro, new cell resource for heterograft on mouse liver diseases, and a new platform for researches on immune rejection of heterogeneous cell transplantation.     

番茄叶组织培养中愈伤组织形成和器官发生的细胞学和微形态学研究

以番茄叶外植体为材料,研究了不同的生长素和细胞分裂素及其浓度配比对叶外植体培养行为的影响;同时,利用细胞学和扫描电子显微镜技术观察了愈伤组织形成和器官发生过程。结果表明,不同种类及浓度配比的生长素和细胞分裂素直接影响愈伤组织的物理状态、大小和形成的速度以及器官分化的频率和速度。叶外植体切口处的叶肉细胞,维管薄壁细胞和维管束上方的少数叶肉细胞首先启动脱分化而开始分裂,这些细胞的活跃分裂和分化导致在外植体表层形成由薄壁细胞、维管组织和无分化状态的表层分生细胞团组成的愈伤组织。而不定芽则通过愈伤组织的薄壁细胞再次脱分化和再分化活动而形成,为“外起源”。认为存在由植物激素决定的“无分化活性”和“有分化活性”二种性质的愈伤组织。     

Ontogeny of the proventitious epicormic buds in Quercus petraea.

In the present work, we described the fate of proventitious epicormic buds on the trunks of 40-year-old Quercus petraea trees and in parallel the vascular trace they produced in the wood. Our results show that small and large individual epicormic buds can survive as buds for 40 years and that both are composed of a terminal meristem and scales. Meristematic areas are detected in the scale axils of small buds; in addition to these meristems the large buds also have secondary bud primordia. The small buds are connected to the pith of the main stem by a unique trace, whereas the large buds are connected by one or multiple traces. A single trace might imply that the whole bud is still alive and multiple traces might indicate that the terminal meristem has died. In the latter case, each trace is connected to a secondary bud of the large bud. The buds found in a cluster are composed of a terminal meristem and scales with axillary meristems in the scale axils. A cluster is connected to the pith of a stem either by a unique trace when it seems to be the result of partial abscission of an epicormic shoot or multiple traces when it might have originated from an epicormic bud in which the terminal meristem has died. Whatever the type of the bud, the vascular trace in the bark is composed of a cambium, secondary xylem and parenchyma cells and the trace present in the wood had parenchyma cells with vestiges of secondary xylem. Each year, the vascular trace should be produced in the bark by the cambium of the tree but not by the bud itself. On 40-year-old Q. petraea, we observed a proliferation of epicormic buds and in parallel a multiplication of the number of vascular traces in the trunk, but the knots caused by the traces of epicormic buds in the wood, either as individuals or in clusters, are minor since their colours are only slightly darker than those of woody rays and they are less than 2 mm in diameter. The knots will appear when epicormic buds develop into shoots. Received: 30 March 1999 / Accepted: 09 June 1999     

Composition and fine structure of minor veins inTetragonia leaf

Summary Mesophyll containing the minor veins from leaves ofTetragonia expansa Murr. was examined in preparation for a study of effects of beet yellows virus on the leaf tissues of this plant. The sieve elements throughout the minor veins exhibit the characteristics commonly found in this type of cell in dicotyledons. The cells are connected with one another by sieve plates and with contiguous parenchyma cells by branched plasmodesmata. Mature sieve elements are enucleate and lack ribosomes. No tonoplast was discerned in these cells. Mitochondria, plastids, and sparse endoplasmic reticulum are retained in mature cells. The plastids, which contain a massive fibrous ring of proteinaceous material, resemble the sieve element plastids ofBeta. The P-protein in the sieve elements is occasionally composed of tubules; more commonly it is represented by loose helices. The tracheary elements have scalariform secondary thickenings. In regions free of these thickenings, the primary wall largely disintegrates; only some loosely arranged fibrils remain. The mesophyll and vascular parenchyma cells contain the various organelles characteristic of living plant cells but vary in degree of vacuolation and in density of cytoplasm. Some vascular parenchyma cells have particularly dense protoplasts. They contain numerous ribosomes and their background matrix consists of a dense population of fine fibrils. Occasional vascular parenchyma cells contain the tubular spiny cell component first recognized inBeta. This work was supported in part by National Science Foundation grant GB-5506.     

Morphological and anatomical features of Cuscuta pedicellata and C. campestris

Observations on morphological and anatomical features of Cuscuta pedicellata and, to a lesser extent, C. campestris have been made at different stages of their life-cycles. The seedling is filiform with a bulbous radicular end which collapses early. The simple shoot apex is green and photosentitive. Initial "nutation" is followed by "creeping" over the substrate. Host plants less than about three weeks old seem not to be attacked by Cuscuta seedlings. When haustorial contact is established the shoot apex differentiates into buds and scale leaves. The chlorophyll disappears and stomata, which are lacking in the seedling, develop. The apical growth rate increases strongly by frequent cell division and - elongation. This is reflected anatomically by the formation of "cell families" in rows. Weakening and flowering of the host plants are followed by flowering of the parasite. Greening of stem segments of Cuscuta occurs during formation of haustoria and after death of the host. Stem anatomy is characterized by a tripartite cortex in which the middle layer consists of thin-walled angular cells. Characteristic are also the voluminuous intercellular spaces, the cortical and perivascular laticifers, and the central position of the small vascular bundles. Observations on self-parasitism were made. The epidermis of the haustorial cushion elongates and the cytoplasm is mainly positioned towards the host. Pseudo-intercellular spaces are formed between the epidermal cells. The haustorium connects the phloem of the two plants, but vascular elements of any kind have not been observed.     

Distribution of pectin and arabinogalactan protein epitopes during organogenesis from androgenic callus of wheat

The distribution of several arabinogalactan protein and pectic epitopes were studied during organogenesis in androgenic callus of wheat. In cell wall of mature and degenerating parenchyma cells, the arabinogalactan epitopes JIM4, JIM14, JIM16 or LM2 were expressed differently according to the cells location. LM2 was observed also in meristematic cells of regenerated shoot buds and leaves. Anti-pectin JIM7 labelled the wall of meristematic cells but fluorescence was strongest in outer walls of surface cells of callus and shoot buds coated by extracellular matrix surface network (ECMSN). During leaves growth the ECMSN disappeared, and JIM7 fluorescence decreased. JIM5 epitope was abundant in the cell walls lining the intercellular spaces of callus parenchyma and in tricellular junctions within regenerated buds and leaves.     

THE FLORAL AND EXTRA-FLORAL NECTARIES OF PASSIFLORA. II. THE EXTRA-FLORAL NECTARY

Extra-floral nectaries of nine species of Passiflora were studied with light and electron microscopy prior to and during secretion. There is no evidence of ER or Golgi participation in the secretion of nectar. The vascular tissue supplying the nectary is characterized by companion and phloem parenchyma cells which are usually larger than the sieve elements, a configuration similar to that found in leaf minor veins. In the petiolar nectaries, large masses of membrane-bound protein are commonly found in these cells. This protein is absent in laminar nectaries.     

Structure and Development of the Axillary Complex and Extrafloral Nectaries in Capparis retusa Griseb.

Abstract: The structure, organization and development of the axillary complex and extrafloral nectary in Capparis retusa Griseb. was analysed for the first time. The axillary complex presents three uniserial descending buds. Subordinated shoots originate from the distal and middle bud, while the proximal bud is usually quiescent. Close to the top of the axillary complex there is a subglobulous and umbilicated extrafloral nectary, normally visited by nectivore ants; a chronological coincidence between secretion, production and ant patrolling activities has been observed. The nectary structure differentiates at the second caulinar node, from an axillar meristem separated from the surrounding cells by a shell zone. On the fourth node a remarkably developed nectary primordium can be observed, inside which procambial strands develop acropetally. In the central region of the nectary primordium homogenous parenchyma differentiates progressively, later acquiring characteristics of nectariferous tissue. The mature nectary is vascularized by xylem and phloem, and the procambial differentiation is completed in a basipetal way. The first serial bud differentiates at the third node, from meristem cells near the base of its supporting leaf. The complex nodal structure with three buds completes its development at the eighth caulinar node. Ramular traces are observed as vascular semicylinders penetrating into the base of the buds to constitute a vascular system similar to that of the shoot. The scheme is repeated in the extrafloral nectary, giving rise to prolific branching in the periphery of the nectariferous tissue.     

灰叶胡杨根蘖繁殖的形态解剖学特征

利用常规石蜡切片法对灰叶胡杨(Populus pruinosa)根蘖繁殖特性进行形态解剖学研究。结果表明: 灰叶胡杨横走侧根由周皮、次生维管组织和四原型的初生木质部构成, 具有次生维管组织中维管射线、次生韧皮薄壁组织发达的结构特征。灰叶胡杨的根蘖繁殖源于横走侧根上不定芽的发生及生长发育。不定芽起源于横走侧根的木栓形成层, 木栓形成层经细胞分裂活动形成不定芽原基, 不定芽原基细胞分裂和生长分化形成在横走侧根表面可观察到的不定芽, 进而生长发育为根蘖苗。不定芽的发生具有同步或非同步的时间特征和单点或多点聚集的空间分布特点, 在生长发育过程中其基部可以产生新的不定芽。不定芽发生、分布和生长特点是根蘖苗大小不一、密集丛生的内在原因, 表明灰叶胡杨具有较强的根蘖繁殖能力。