Development, Histochemistry and Ultrastructure of Gum-resin Ducts in Commiphora mukul Engl.

Gum-resin ducts are present in the primary and secondary phloemof Commiphora mukul Engl. The important gum-resin, known commerciallyas ‘guggul’, is secreted and collected in ductswhich develop schizogenously. The duct initials have dense cytoplasm,large nuclei, increased cytoplasmic RNA and proteins. The lumenof newly-formed ducts widens accompanied by anticlinal divisionsand subsequent tangential elongation of epithelial cells. Histochemicaltests reveal that the epithelial cells have apparently largeamounts of proteins, cytoplasmic RNA, and DNA in the nucleus.Lipid globules are also present in these cells. Epithelial cellwalls in contact with the duct are thin and of a loose fibrillarmesh. Microtubules, randomly oriented in the epithelial cellsare always parallel and adjacent to the wall. The cytoplasmis rich in ribosomes, endoplasmic reticulum, mitochondria, plastidsand vacuoles containing osmiophilic substances. At the peripheralregion of the duct, electron-transparent bodies containing densely-stainedmaterial are present close to the tangential wall.     

Development and Structure of Primary Secretory Ducts in the Stem of Commiphora wightii (Burseraceae)

Development of gum-resin ducts, sites of resin synthesis inthe epithelial cells and elimination of resin from the protoplasthave been studied in the stem of Commiphora wightii. Formationof an intercellular space amongst a group of densely stainedprocambial cells signals the initiation of a duct. It widensby anticlinal divisions of the epithelial cells and also bytheir further separation along the radial walls. The numerousplastids with varying morphological shapes have an electrondense matrix. Starch granules present in the amyloplasts showevidences of exocorrosion. Mitochondria in the epithelial cellsof developing and mature ducts have well developed, swollencristae. Osmiophilic material originates in association withthe golgi-derived vesicles at its maturing face. It is alsoobserved in close association with plastids, mitochondria andvacuoles, thereby plausibly involving them in the process ofresin formation. The resinous material is eliminated from thecytoplasm by vesicles enveloped by plasmalemma prior to theirdischarge into the apoplast. Myelin-like multilamellate structuresobserved along the inner tangential wall may aid in the secretionof resin across the wall. Commiphora wightii, primary secretory ducts, epithelial cells, ultrastructure, gum-resin secretion     

ULTRASTRUCTURE OF THE SECRETORY DUCTS OF RHUS GLABRA L.

The infrastructure and development of the secretory ducts were studied in the secondary phloem of Rhus glabra L. The ducts were found to develop schizogenously. The electron microscope observations may explain the view of several previous authors of schizo-lysigenous development of the duct lumen in the Anacardiaceae. The secreted material consists of lipophilic and polysaccharide substances. The electron micrographs suggest that the lipophilic substances arise in plastids, ER cisternae, Golgi vesicles, and mitochondria. The polysaccharide constituents apparently originate from the outer wall layers of the epithelial cells. The wall layers facing the lumen of the duct disintegrate and form, together with the secreted osmiophilic droplets, the gum-resin. Numerous microtubules were found along walls of the epithelial cells.     

In vitro Organogenesis and Plantlet Formation in Cashew (Anacardium occidentale L.)

Rapid induction of multiple plantlets of Anacardium occidentalewas obtained from cotyledonary explants. Lin and Staba medium,containing 05 mg 1^–1 of both IAA and KN, promoted directorganogenesis and plantlet formation. Plantlets developed froman organized hemispherical mass of meristematic tissue arisingfrom single epidermal cells. Bipolar differentiation resultedin the formation of shoot and root primordia in a sequentialmanner Anacardium occidentale L., cashew, cotyledon explant, organogenesis, plantlet formation     

Ultrastructure of the Resin Ducts of Mangifera indica L. (Anacardiaceae). 3. Secretion of the Protein-polysaccharide Mucilage in the Fruit

Mango fruit ducts secrete a protein-carbohydrate mucilage inaddition to lipophilic material. This mucilage is secreted inspecial duct regions. Loops of ER elements seem to delimit cytoplasmicportions rich in ribosomes forming pseudo-vacuoles which eventuallybecome bound by a single membrane of ER origin. It is suggestedthat the protein is produced and accumulates in the pseudo-vacuoleswhich become storage bodies. Carbohydrates are added to thecontent of these bodies by Golgi vesicles. The cytoplasm becomesosmiophilic and contracts before disintegration, and the mucilagepasses into the space between plasmalemma and cell wall. Afterthe cell breaks down the mucilage is released into the ductcavity. Mangifera indica L., mango, Anacardiaceae, resin ducts, secretion, mucilage, ultrastructure     

Studies on the Ultrastructure at the Interface of the Cotyledon and the Testa of Cashew Nut (Anacardium occidentale L.) Before and After Industrial Processing

A cuticle was found for the first time on the surface of theepidermis of the cotyledon of Anacardium occidentale L., andthe ultrastructure of the cuticle was established as being narrowand lamellate. The major ultrastructural features of the previouslyundescribed testa were the layers of crushed, lignified cellsin the endosperm layer, and an associated, electron-dense complexat the interface. Changes in the ultrastructure of the outerlamella of the cuticle, the sub-epidermal layer of the cotyledonand the lining complex of the testa were observed after removalof the testa by industrial processing. The basic ultrastructureof the endosperm layer of the testa and the inner lamella ofthe cuticle were found to be least affected by the processing.     

Tapetal Cell Changes and Sporoderm Development in Rhigozum trichotomum (Burch.)

Rhigozum trichotomum is a perrenial woody shrub which is indigenousto the arid regions of southern Africa. Primexine developmentis initiated while the microspores are still enclosed by callose.This is followed by the appearance of probacula which give riseto the tectum, bacula and nexine. At the time of callose dissolution,the exine pattern is well established and intine developmenthas been initiated. During the tetrad stage, the protoplastsof the tapetal cells exhibit shrinkage while conspicuous stacksof rough endoplasmic reticulum become evident in their cytoplasm.These stacks produce numerous vesicles which are associatedwith lipid globules and which migrate to the tapetal/locularwall where, it is suggested, they give rise to the pro-orbicules.The pro-orbicules become coated with an osmiophilic substance,probably sporopollenin, and are released into the thecal fluidto become intimately bound to the exine, Here they are strippedof the osmiophilic layers which appear to be incorporated intothe sporoderm. Rhigozum trichotomum (Burch.), sporoderm, pollen wall, exine, orbicules, pro-orbicules, sporopollenin, tapetum     

Development, Ultrastructure and Secretion of Gum Ducts in Lannea coromandelica (Houtt.) Merrill (Anacardiaceae)

In Lannea coromandelica (Houtt.) Merrill, the gum ducts in theprimary phloem of the stem initiate and develop schizogenously.Formation of an intercellular space amongst a group of denselystained phloem procambial cells signals the initiation of aduct. Initiation of a duct starts by dissolution of the middlelamella of the walls. It widens by separation of cells alongthe radial walls by swelling and dissolution of the middle lamella.During separation of radial walls dictyosomes and paramuralbodies are observed in the peripheral cytoplasm at the siteof dissolution. Plasmodesmata occur in the radial and innertangential walls of epithelial cells of developing gum ducts.The epithelial cells have a dense cytoplasm and contain roughendoplasmic reticulum, ribosomes, polysomes, mitochondria withswollen cristae, plastids with poorly developed membranes, dictyosomesand vesicles. Dictyosomes and rough endoplasmic reticulum seemto be involved in the secretion of the gum. The polysaccharidegum constituents apparently originate from the outer wall layersof the epithelial cells. Following gum secretion, the epithelialcells degenerate. Lannea coromandelica (Houtt.) Merrill, Anacardiaceae, gum ducts, ultrastructure, gum secretion     

Ultrastructure of the Resin Ducts of Mangifera indica L. (Anacardiaceae). 1. Differentiation and Senescence of the Shoot Ducts

A detailed electron microscope study has led to the conclusionthat the resin ducts of the shoot of Mangifera indica L. developlysigenously. This study has also established several characteristicswhich can serve as criteria for a clear distinction betweenschizogenous and lysigenous cavities. The main characteristicsof lysigenous cavities are: (1) The presence of disorganized cytoplasm in the duct cavity. (2) The presence of wall remains attached to the wall of livingepithelial cells facing the cavity. (3) The presence of specific intercellular spaces at the cellcorners facing the duct lumen. Duct development starts with the disintegration of a file ofcells forming an initial cavity. Later the cells lining thiscavity differentiate into cells secreting lipophilic compounds.As a result of growth and differentiation of the tissues aroundthe duct, its lumen becomes compressed and comes to resemblea branched narrow slit. Such a slit may wrongly be regardedas an initial stage of a schizogenous duct. Disintegration ofepithelial cells occurs throughout all stages of development.Neighbouring cells partly fill the space which is released bydisintegrating cells. At the end of the stage of secretion thecytoplasm of all epithelial cells darkens, preceding their disintegration.This darkening is a gradual process which begins in the vicinityof ribosomes. When all dark epithelial cells disintegrate thecavity widens and the neighbouring parenchyma cells substitutefor the secretory epithelium without undergoing any significantchange in their cytoplasm. Mangifera indica L., mango, resin ducts, ultrastructure     

Ultrastructure of the Resin Ducts of Mangifera indica L. (Anacardiaceae). 2. Resin Secretion in the Primary Stem Ducts

The resin of the mango stem consists mainly of terpenes. Theterpenes seem to be produced primarily by plastids, termed heresecretoplasts. At the beginning of the process of secretion,osmiophilic droplets are seen at the envelope of the secretoplastsand at elemints of periplastidal ER. In addition, such dropletsoccur also at Golgi bodies and occasionally in association withmitochondria. Later osmiophilic material fills the well-developbdER, which at this stage is mainly tubular. It appears that theER is involved in the transport of the sareted material towardsthe plasmalemma. Mangifera indica L., mango, Anacardiaceae, resin, resin ducts, secretion, secretoplasts, ultrastructure     

Observations on the origin of two substances produced by the vitellaria in Gorgoderina attenuata

The vitelline cells in Gorgoderina attenuata produce two qualitatively distinct substances. One substance assumes the form of individual, dense, osmiophilic globules. Many globules are contained in a single vesicle. The other substance is an amorphous mass of medium density that completely fills a vesicle. Observations indicate that the dense, osmiophilic globules develop in association with a system of small, contiguous, ribosome-free vesicles. It is suggested that this system of vesicles constitute a Golgi apparatus for these cells. The amorphous mass substance develops in vesicles which appear to be derived from endoplasmic reticulum. Close association between the amorphous mass vesicle and mitochondria are commonly observed.     

Ultrastructural localization of a diprenylated isoflavone in Rhizobium lupini-Lupinus albus symbiotic association

Polyclonal IgGs raised against the diprenylated isoflavone,2'-hydroxylupalbigenin were used in an immunocytochemical studyof the root and nodule tissues of white lupin (Lupinus albusL.). In the roots, the antigen was detected in the secondarywalls of both xylem vessels and pericycle cells. Examinationof nodules revealed the presence of the antigen in the innercortex, associated with a neoparietal material which is depositedas globules on the cell wall and occluding the intercellularspaces. The discrete location of the diprenylated isoflavonein specialized cytoplasmic organelles suggests that its compartmentationwithin the wall is mediated by membrane vesicles. In the infectedcells, more than half of the bacteroids exhibited a specificlabelling of their inner core associated with a central fibrillarsystem, and sometimes surrounding an electron-dense nucleoidregion. These results suggest that 2'-hydroxylupalbigenin, andpossibly other prenylated isoflavones, may play an importantrole as a biochemical factor in early symbiotic events otherthan nod gene induction or inhibition. Its putative biologicalfunctions in the post-infectional phases of symbiosis are discussed. Key words: Bacteroid, 2'-hydroxylupalbigenin, in situ localization, Lupinus albus, nodules     

The development and ultrastructure of gum ducts inCitrus plants formed as a result of brown-rot gummosis

Summary Young stems ofCitrus plants were infected with the fungusPhytophthora citrophthora. The effect of the infection on gum duct development was studied. The following sequence of structural changes was observed in the cambial zone: 1. The middle lamellae between layers of xylem mother cells dissolve forming duct cavities. 2. The cells around the duct cavities differentiate into epithelial cells rich in cytoplasm. 3. The amount of Golgi bodies and associated vesicles increases. The vesicles and small vacuoles, some of which seem to originate from the fusion of Golgi vesicles, contain fibrillar material that stains for polysaccharides. Vesicles and vacuoles appear to fuse with the plasmalemma. Material staining positively for polysaccharides accumulates between the plasmalemma and cell wall, and penetrates the latter. 4. The protoplast shrinks and the space below the cell wall, which contains polysaccharides, increases in volume. 5. After a period of 10 days or more the gum ducts become embedded in the xylem, and the activity of the epithelial cells ceases. The cell walls of many of them break, and the gum still present in the cells is released.     

Changes in cellular composition of kidney collecting duct cells in rats with lithium-induced NDI

Lithium treatment for 4 wk caused severe polyuria, dramatic downregulation in aquaporin-2 (AQP-2) expression, and marked decrease in AQP-2 immunoreactivity with the appearance of a large number of cells without AQP-2 labeling in the collecting ducts after lithium treatment. Surprisingly, this was not all due to an increase in AQP-2-negative principal cells, because double immunolabeling revealed that the majority of the AQP-2-negative cells displayed [H⁺]ATPase labeling, which identified them as intercalated cells. Moreover, multiple [H⁺]ATPase-labeled cells were adjacent, which was never seen in control rats. Quantitation confirmed a significant decrease in the fraction of collecting duct cells that exhibited detectable AQP-2 labeling compared with control rats: in cortical collecting ducts, 40 ± 3.4 vs. 62 ± 1.8% of controls (P < 0.05; n = 4) and in inner medullary collecting ducts, 58 ± 1.6 vs. 81 ± 1.3% of controls (P < 0.05; n = 4). In parallel, a significant increase in the fraction of intercalated ([H⁺]ATPase-positive) cells was shown. Urine output, whole kidney AQP-2 expression, cellular organization, and the fractions of principal and intercalated cells in cortex and inner medulla returned to control levels after 4 wk on a lithium-free diet following 4 wk on a lithium-containing diet. In conclusion, lithium treatment not only decreased AQP-2 expression, but dramatically and reversibly reduced the fraction of principal cells and altered the cellular organization in collecting ducts. These effects are likely to be important in lithium-induced nephrogenic diabetes insipidus. nephrogenic diabetes insipidus; aquaporin; exchanger     

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     

The Ultrastructure and Analytical Microscopy of Silicon Deposits in the Roots of Saccharum officinarum (L.)

Silicon accumulation in the endodermis of the ‘set’and ‘shoot’ roots of Saccharum officinarum (L.)were investigated by scanning electron microscopy and electron-probemicroanalysis. Silicon microassay was also carried out by meansof the Corinth analytical microscope (CORA). Aggregates arelargely associated with the inner tangential wall (ITW) of theendodermis and their formation is basically similar to thoseseen in Sorghum bicolor (L.) Moench. In contrast to Sorghumthe earliest deposits in Saccharum appear in wall strata wellwithin the cell wall cytoplasm interface. An additional layerof silicon was also located along the endodermal pericycle boundaryextending some distance along the middle lamella of the radialwalls. The results are discussed in relation to those of previous studiesof silicon accumulation in endodermal cells and to possiblefactors affecting such accumulations.     

Electron-probe Microanalysis Studies of Silicon in the Elongating Basal Internodes of Avena sativa (L.), Hordeum sativum (Jess.) and Triticum aestivum (L.)

Silicon deposits in the elongating basal internodes of almostmature, field grown specimens of Avena sativa, Hordeum sativumand Triticum aestivum were investigated using electron-probemicroanalysis. In A. sativa and H. sativum silicon was foundto be confined to the cells in the endodermal layer, being presentwithin the inner tangential and radial walls, and occasionallyin the outer tangential wall. In T. aestivum some silicon wasalso located in walls of cells surrounding the vascular bundles. The anatomy of the internodal tissues is discussed for the threespecies from light micrographs. The endodermal layer is discontinuousin A. sativa and H. sativum, in the former species it partlyextends around individual vascular bundles. In T. aestivum itforms a complete cylinder around the stelar region and alsoshows considerably more thickening of the inner tangential wallthan in the other species. The results are discussed in relation to the anatomy of theinternodal tissues and the possible function of silicon in theendodermis. Avena sativa L., Hordeum sativum Jess, Triticum aestivum L., oat, barley, wheat, silicon deposition, electron-probe microanalysis     

Ultrastructure of Resin Ducts in Pinus halepensis Development, Possible Sites of Resin Synthesis, and Mode of its Elimination from the Protoplast

Development of the resin duct cavity, sites of resin synthesisin the epithelial cells and elimination of resin from the protoplastwere studied in roots of young Pinus halepensis seedlings. Itis suggested that the Golgi bodies are involved in dissolutionof the middle lamella in the region of the future duct cavityby secretion of lytic enzymes into the cell walls. In earlystages of duct development osmiophilic droplets were observedin plastids, periplastidal and cytoplasmic ER, Golgi vesicles,mitochondria, nuclear envelope and in the cytoplasm. In thelatter they were often observed to be surrounded by a membrane.Electron micrographs suggested that elimination of resin dropletsfrom the protoplast occurs by their becoming surrounded by plasmalemmainvaginations.     

The Ultrastructural Aspect of Tapetum and Ubisch Bodies in Anemarrhena asphodeloides

From ontogeny of tapetum in Anemarrhena asphodeloides, the ultrastructnral features of tapetal cells are as follows: 1. The profuse rough endoplasmic reticula are often closely associated with lipid bodies and vesicles, and linking each other into compound organelles. This is one of the striking features in Anemarrhena tapetal cell. 2. After meiosis of the micro- spore mother cell, the tapetal cytoplasm contains a large number of vesicles, in which the electron opaque substances are accumulated. Then they fuse to form a large zone of storage material similar to lipid bodies. Before accumulation of opaque material, these vesicles in the tapetal cytoplasm are larger than those in elaioplast (see Plate II, Fig. 2). 3. During stage of pollen maturation the tapetal cytoplasm becomes disorganized and the cells are almost occupied by the elaioplasts at various degree of development. On the basis of the report of Dickinson (1973), the formation of a pollen coatings of Lilium is different from that of Raphanus. The osmiophilic bodies in the former have originated from membrane lamellae or membranous system of plastid, and those in the latter are formed from the plastid vescles. It is intereting to note that the mode of origin of the plastid osmiophilic bodies in Anemarrhena is rather similar to that of Raphanus than to Lilium. About the origin of the pro-Ubisch bodies in tapetal cytoplasm of Anemarrhena studies revealed that a large number of the medium electron dense bodies appear in the tapetal cytoplasm. This is the first sign of the formation of the pro-Ubisch bodies and its character is very similar to spherosome in many respects. From many ultrasections, it can be seen that the ER profile is closely associated with the pro-Ubisch bodies. Thus we can conclude that the proubisch bodies of Anemarrhena are derived from rough endoplasmic reticulum. Although Heslop-Harrison et al. (1969) has considered that the compound Ubisch bodies do not occur in Lilium, there are prominent aggregation of Ubisch bodies in Anemarrhena, same as reported in Oxalis (Cariel, 1967), Silene (Heslop-Harrison, 1963a) and Helleborus (Echlin et al., 1968). After investigation on certain angiosperm in 1972, Gupta and Nanda have reported that the peritapetal membrane belonging to tapetum of secretory type lies against the inner tang- ential wall; in the plasmodial type of tapetum, it is formed on the outer tangential wall. But in some species of Poaceae and Solanaceae, the peritapetal membrane is formed on both sides of the tapetal cells (Banerjee, 1967; Reznickov & Willemse, 1980). In the secretory tapetum of Anemarrhena, the peritapetal membrane, which do not comply with the conclusion of Gupta & Nanta (1972), is formed on outer tangential wall.     

Vascular Occlusions in the Stem of Ailanthus excelsa Roxb.

The stem of Ailanthus excelsa Roxb. (Simaroubaceae) may developvascular occlusions and gum-resin cavities in the xylem as aresponse to injury and infection. Fungal hyphae are observedin the vessel lumen and in the adjacent parenchyma cells. Theocclusions appeared in various forms and showed varying chemicalcomposition. The chemical nature of the occluding material differedfrom that of the exudate formed in the cavities. The majorityof occlusions contained lipids, protein, polysaccharides, phenolics,lignin and probably pectin, whereas, the exudate contained lipids,protein and four soluble sugars. All the components of the occlusionexcept lignin and pectin appear to have been formed in the parenchymacells adjacent to the vessel and migrated to vessel lumen throughthe vessel wall pits. The different constituents migrate intothe vessel lumen independently where they mix to form occlusions. Ailanthus excelsa Roxb., vascular occlusions, lignin, fluorescence, exudation