Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “vascular bundle”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed2006

Catalyst transport in corn stover internodes: elucidating transport mechanisms using Direct Blue-I.

The transport of catalysts (chemicals and enzymes) within plant biomass is believed to be a major bottleneck during thermochemical pretreatment and enzymatic conversion of lignocellulose. Subjecting biomass to size reduction and mechanical homogenization can reduce catalyst transport limitations; however, such processing adds complexity and cost to the overall process. Using high-resolution light microscopy, we have monitored the transport of an aqueous solution of Direct Blue-I (DB-I) dye through intact corn internodes under a variety of impregnation conditions. DB-I is a hydrophilic anionic dye with affinity for cellulose. This model system has enabled us to visualize likely barriers and mechanisms of catalyst transport in corn stems. Microscopic images were compared with calculated degrees of saturation (i.e., volume fraction of internode void space occupied by dye solution) to correlate impregnation strategies with dye distribution and transport mechanisms. Results show the waxy rind exterior and air trapped within individual cells to be the major barriers to dye transport, whereas the vascular bundles, apoplastic continuum (i.e., the intercellular void space at cell junctions), and fissures formed during the drying process provided the most utilized pathways for transport. Although representing only 20-30% of the internode volume, complete saturation of the apoplast and vascular bundles by fluid allowed dye contact with a majority of the cells in the internode interior.

Azo Compounds↗
PubMed2004

Raman and cathodoluminescence spectroscopic investigations on Permian fossil wood from Chemnitz--a contribution to the study of the permineralisation process.

Samples of different three-dimensionally preserved fossil plants (Medullosa sp., Dadoxylon sp., Calamodendron striatum, Psaronius sp.) from the Lower Permian petrified forest of Chemnitz were examined with regard to their chemical composition and structural order. Raman spectroscopy and cathodoluminescence microscopy are shown to be powerful tools for such investigations. Silicified wood from Chemnitz-Hilbersdorf generally shows yellow cathodoluminescence (CL) of the cell walls and only weak yellow-brownish CL of the cell lumina. By time-resolved cathodoluminescence spectroscopy, a secondary mineralisation of hydrothermal origin was recognized. The latter is shown by short-lived blue CL at the cell walls extinguishing the yellow signal. Therefore, after the primary silicification step a secondary mineralisation step initiated by hydrothermal processes, seems to have taken place at probably slightly higher temperatures. The resulting silica matrix consists of phanerocrystalline and microcrystalline alpha-quartz as well as microcrystalline moganite, both partially associated with iron oxides. Dadoxylon sp. is a prominent example for parallel permineralisation by alpha-quartz and fluorspar, which is outstanding for the Chemnitz Petrified Forest. CL on this samples shows parallel silicification and fluoritisation, followed by infiltration of iron oxides. Permineralised samples show very low percentage of original organic remains. The seed fern Medullosa, for example, shows dispersed carbon, which is mainly restricted to the centres of the typical star-shaped vascular bundles. Raman spectroscopy revealed that these carbonaceous particles are of an anthracite structure. For experimental confirmation coal samples of different rank, especially anthracite from different geological times and localities, were studied by means of Raman spectroscopy. The remaining pith of the vascular bundles is white-coloured and consists of alpha-quartz and moganite, whereas surrounding tracheides exhibit white and reddish coloured parts. The reddish parts, mainly found in the rays, additionally contain alpha-Fe2O3 and Fe3O4 among the SiO2 polymorphs of alpha-quartz and moganite. Sometimes iron oxides could have dominated permineralisation processes as the peak intensities of distinct parts of the samples suggest.

Ferns↗
PubMed1978

Sucrose in the free space of translocating maize leaf bundles.

Following exposure of portions of mature maize (Zea mays L.) leaf strips to (14)CO(2), xylem exudate from the leaf strips contained [(14)C]sucrose. Sucrose was the only sugar in the xylem exudate which was obtained from the cut surface of the leaf strips by reducing the external pressure. The sucrose found in the xylem exudate apparently was obtained from the free space of the vascular bundles, its concentration amounting up to 0.25%. When [(14)C]glucose or [(14)C]fructose was supplied in the dark to one end of a maize leaf strip, each was taken up by the xylem, and transported to the opposite end. Xylem exudate from such leaf strips contained (14)C-labeled sucrose in addition to the (14)C-labeled hexose. The results of this study support the view that sucrose is loaded into the companion cell-sieve tube complexes from the apoplast of the vascular bundles in the maize leaf.

Journal Article↗
PubMed2005

How are leaves plumbed inside a branch? Differences in leaf-to-leaf hydraulic sectoriality among six temperate tree species.

The transport of water, sugar, and nutrients in trees is restricted to specific vascular pathways, and thus organs may be relatively isolated from one another (i.e. sectored). Strongly sectored leaf-to-leaf pathways have been shown for the transport of sugar and signal molecules within a shoot, but not previously for water transport. The hydraulic sectoriality of leaf-to-leaf pathways was determined for current year shoots of six temperate deciduous tree species (three ring-porous: Castanea dentata, Fraxinus americana, and Quercus rubra, and three diffuse-porous: Acer saccharum, Betula papyrifera, and Liriodendron tulipifera). Hydraulic sectoriality was determined using dye staining and a hydraulic method. In the dye method, leaf blades were removed and dye was forced into the most proximal petiole. For each petiole the vascular traces that were shared with the proximal petiole were counted. For other shoots, measurements were made of the leaf-area-specific hydraulic conductivity for the leaf-to-leaf pathways (k(LL)). In five out of the six species, patterns of sectoriality reflected phyllotaxy; both the sharing of vascular bundles between leaves and k(LL) were higher for orthostichous than non-orthostichous leaf pairs. For each species, leaf-to-leaf sectoriality was determined as the proportional differences between non-orthostichous versus orthostichous leaf pairs in their staining of shared vascular bundles and in their k(LL); for the six species these two indices of sectoriality were strongly correlated (R2=0.94; P <0.002). Species varied 8-fold in their k(LL)-based sectoriality, and ring-porous species were more sectored than diffuse-porous species. Differential leaf-to-leaf sectoriality has implications for species-specific co-ordination of leaf gas exchange and water relations within a branch, especially during fluctuations in irradiance and water and nutrient availability.

Biological Transport↗
PubMed1979

Visualization of intrarenal catecholamine-containing elements: fluorescence histochemistry and electron microscopy.

Fluorescence histochemistry and electron microscopy were used to study catecholamine-containing elements in rat and cat kidneys. There were fluorescent nerve plexuses associated with the arterial system of the renal cortex from which nerves extended into the medulla forming dense networks in the vascular bundles of the outer part of the medulla. Also, there were small cells found singly and in clusters which emitted the blue fluorescence characteristic of catecholamine-containing cells. These cells were associated with the periarterial nerve plexuses and were frequently encountered in the cat medullary vascular bundles. Electron microscopy of the cat renal medulla revealed processes with the structure of typical adrenergic terminals and other processes that resemble small intensely fluorescent (SIF) cell processes.

Adrenergic Fibers↗
PubMed2003

[Accelerated maturation of expanded prefabricated flaps by use of vascular endothelial growth factor and basic fibroblast growth factor in rabbits].

OBJECTIVE: To evaluate the effect of vascular endothelial growth factor(VEGF) 165 or basic fibroblast growth factor (bFGF), which was slowly-released in fibrin glue patch, on expanded prefabricated flaps in rabbits to facilitate the neoangiogenesis process. METHODS: A total of 53 rabbits were divided randomly into 6 groups. The central auricular vascular bundle of the ear was implanted into the expanded prefabricated flap as the pedicle. Fibrin glue, sandwiched between the expander and the implanted vessels, was adopted for topical delivering and slow-releasing of VEGF(625 ng) or bFGF(2880U). After 14 days, the island flap with the implanted vascular bundles as the pedicle was elevated, sutured back to its original position and then harvested more 3 days later. Neoangiogenesis was measured by digital recording of survival area, laser Doppler flowmetry, PCNA immunohistochemistry, TUNEL, ink and PbO infusions. RESULTS: When compared with the other groups, flap survival improved; neoangiogenesis of flaps increased, together with the blood flow enhanced in the groups applied growth factors. The reduced cellular apoptosis and the increased proliferation were also observed. CONCLUSION: VEGF or bFGF slowly-released by fibrin glue shows the potential to facilitate neoangiogenesis and accelerate maturation of the expanded prefabricated flap.

Animals↗
PubMedDate not supplied

[Value and limits of CT in the preoperative assessment of primary malignant tumors of bone. Observations in 138 cases].

To estimate the capabilities and limitations of CT in the preoperative evaluation of malignant primary bone neoplasms, 138 patients were examined with high resolution CT and subsequently underwent surgery. In all cases a pathologic examination of the surgical specimen was performed, whose results were compared to CT findings. CT appears to yield important diagnostic contribution to preoperative staging. As a matter of fact, CT shows the tumor extension and its relationship to the adjacent anatomical structures, particularly, it shows the involvement of the muscular and vascular bundles, and that of the articular cavity and medullary canal. These data are of primary importance for planning therapy. The commonest CT limitations are: overestimation of the tumor extension, false positives and false negatives when searching "skip" metastases, and, sometimes, inaccurate definition of the relationship between tumor and vascular bundles and/or articular cavities. These limitations may be overcome by using, when necessary, other techniques--i.e. angiography, bone scan and, above all, MR imaging.

Adolescent↗
PubMed1986

The renal microvasculature of the monkey: an anatomical investigation.

Twelve monkeys, Macaca fascicularis and Macaca mulatta, were investigated to study their renal microvasculature. After death, all monkeys were perfused with heparinised isotonic saline to flush their vascular systems. The kidneys were then perfused with silicone rubber and examined. The silicone rubber injections allowed description of afferent arterioles and several efferent vascular patterns observed in the subcapsular, midcortical, and inner cortical regions. The medullary vasculature was particularly interesting in that no particular vascular zonation was observable. Silicone rubber injections indicated the existence of vascular bundles that run parallel to one another from outer medulla nearly to the papillary tip. Branching of descending vasa recta into capillaries, or precapillary vessels, occurs frequently and at all levels of the medulla. Ascending vasa recta are formed from the interbundle capillary plexus and from the plexus at the papillary tip. They ascend primarily within vascular bundles to the corticomedullary junction where these vessels may empty into collecting veins or arcuate veins. In addition, many ascending vasa recta penetrate into the cortex where they drain into the proximal third of interlobular veins. The venous drainage of the cortex appears to be regional, in that the area surrounding an interlobular vein generally drains into it directly via venules or small veins. The arterial and venous morphology of the monkey kidney may be important to the monkey's ability to concentrate urine despite the virtual absence of an inner medullary zone. The potential physiological significance of the monkey's microvasculature is discussed extensively and compared with various other mammals.

Animals↗
PubMed1992

A dominant mutation in the maize homeobox gene, Knotted-1, causes its ectopic expression in leaf cells with altered fates.

Dominant mutations of the Knotted-1 (Kn1) homeobox gene of maize alter the differentiation and growth of cells associated with leaf veins. By analyzing Kn1 transcripts and KN1 protein, we show that the gene is not expressed at high levels during the development of wild-type leaves. Instead, Kn1 is expressed in apical meristems of vegetative and floral shoots, and is downregulated as leaves and floral organs are initiated. Kn1 is also expressed in relatively undifferentiated cells within developing vascular bundles, as well as ground tissue, in immature, unelongated axes of wild-type vegetative and floral shoots. In Kn1-N2 mutant plants, quantitative, but not qualitative differences are apparent in Kn1 transcripts and KN1 protein, consistent with previous observations that dominant Kn1 mutations map to non-coding regions of the gene. Kn1 is expressed ectopically in vascular bundles within developing mutant leaves in a pattern that correlates with the phenotypic alterations produced by the Kn1-N2 mutation. Thus, Kn1 apparently alters the fates of leaf cells in which it is ectopically expressed from an early stage of leaf development. Based on these observations, we hypothesize that Kn1 functions in its wild-type context as a regulator of cell determination.

Fluorescent Antibody Technique↗
PubMed1995

Arabinogalactan proteins in maize coleoptiles: developmental relationship to cell death during xylem differentiation but not to extension growth.

The spatial and temporal expression of arabinogalactan proteins (AGPs) in the coleoptile of maize seedlings was investigated with monoclonal antibodies (MAC207, JIM13, JIM14) raised against particular AGP epitopes in carrot. MAC207 binds to a buffer-soluble AGP fraction of 90-210 kDa that also reacts with beta-glucosyl Yariv reagent and the lectin RCA120. Immunogold-labelling showed that the MAC207 epitope is exclusively localized in the plasma membrane. JIM13 binds to a 120 kDa component of the buffer-soluble AGP fraction localized in the plasma membrane of future sclerenchyma cells and secondary-wall thickenings of future tracheids of vascular bundles. JIM14 binds to a 50 kDa component of the salt-extractable fraction from cell walls localized in the innermost wall layer of sclerenchyma cells. These AGP epitopes demonstrate different temporal expression patterns which do not correlate with extension growth. Auxin had no effect on the amount of soluble AGP from coleoptile sections, containing the growth-controlling epidermis but no vascular bundles, as measured by crossed electrophoresis. Moreover, incorporation of radioactive arabinose, galactose or proline into this fraction was not stimulated by auxin. These results contradict the hypothesis that AGPs function as wall-loosening agents in auxin-mediated extension growth. The results are compatible with the notion that AGPs serve as developmental markers defining particular features of future cell differentiation. The specific association of the epitopes recognized by JIM13 and JIM14 with disintegrating cells suggests that the related AGPs identify those cells of the coleoptile which are committed to programmed cell death.

Cell Death↗
PubMed1990

Monoaminergic innervation of the rat kidney: a quantitative study.

The sympathetic innervation of the renal tubules and vasculature was characterized by measuring the overlap of accumulations of autoradiographic grains (AAGs) on these structures in autoradiograms of kidney sections from rats injected with tritiated norepinephrine. AAG overlap was used as an indirect measure of the innervation of those structures. The renal vasculature showed x 4.5 more AAG overlap than observed on renal tubules. The greatest amount of AAG overlap occurred on afferent arterioles, followed by efferent arterioles, interlobular arteries, cortical capillaries, arcuate arteries, and renal veins. High concentration of AAGs occurred along the vascular bundles of the outer stripe. In the tubular nephron the proximal tubule had the greatest amount of AAG overlap, followed by the cortical thick ascending limb of Henle, the connecting tubule, the distal convoluted tubule, and the collecting duct. It was found that afferent arterioles had significantly higher mean density of AAG overlap than efferent arterioles for the superficial, midcortical, and juxtamedullary (vascular bundles excluded) renal cortex. There was consistently more AAG perimeter facing the interstitium than overlapping the vasculature. These observations, together with the ultrastructural distribution of synaptic vesicles in varicosities, suggest that the interstitium might be an additional pathway of neurotransmitter access to the effector structures.

Animals↗
PubMed1995

Localization of fruit tree viruses by immuno-tissue printing in infected shoots of Malus sp. and Prunus sp.

Immuno-tissue printing protocols for the localization of apple chlorotic leaf spot virus (ACLSV), stem grooving virus (SGV) and plum pox virus (PPV) in shoots of Prunus and Malus in vitro have been established for routine diagnosis in a virus elimination program. Since these viruses belong to different virus genera, the protocols were adapted according to the properties of the virus under investigation. Accumulation of ACLSV was highest in the base of the stem and decreased towards the apex of the shoots. ACLSV was found in the epidermis, the cortex, in the vascular bundles, but seldom in the pith tissue of in vitro apple shoots. ACLSV immuno-tissue printing was as sensitive as ELISA and the intensity of color signals in immuno-tissue prints correlated with absorbance values by two-step ELISA. SGV could be detected by immuno-tissue prints at infectivity levels, where it reacted negative in ELISA. SGV accumulated in the vascular bundles, occurred locally in the parenchymatic tissue, was found in high amounts in young leaves near the meristem, but not within the meristem. PPV was detected in all tissue types of stem sections with an irregular pattern reflecting the in vivo situation causing problems with detection. Discrimination of poorly and heavily infected shoots was possible with the naked eye.

Culture Techniques↗
PubMed1990

Structural changes in spruce and fir needles.

Needles from spruce and fir trees were analyzed for histological changes induced by long-term exposure in open-top chambers to SO(2) and/or O(3) combined with acid rain. Light and electron microscopical evaluation revealed initial structural changes in the vascular bundle of fir needles, with an increased number of crushed sieve cells in the phloem. In addition the walls of young, adaxial sieve cells lacked the typical thickening usually observed in naturally aged needles. These findings may indicate restricted assimilate translocation. The presence of SO(2) in any treatment led to thylakoidal swellings and membrane reductions in the chloroplasts of mesophyll cells near the vascular bundle. This damage pattern resembled alterations caused by nutrient deficiency rather than by the direct action of gaseous pollutants. In general, fir appears to be more sensitive to environmental stress than spruce; this substantiates the findings of previous studies.

Journal Article↗
PubMedDate not supplied

Microlaparoscopic varicocelectomy.

OBJECTIVES: To review the development of laparoscopic varicocelectomy from our initial description in 1986 based in the first pioneering works of K. Semm and to describe our latest microlaparoscopic technique that uses 3 mm instruments. METHODS: We use 3 mm reusable trocars with a specially designed telescope and instruments. One port is in the umbilicus the others are in the flanks at this level. Spermatic vessels are identified by firm traction of the testicle. The peritoneum is incised transversally at this level to dissect and ligate the two or three veins usually found here. To shorten operation time and improve results the vascular bundle is ligated en-bloc and when it is bulky, we divide it into two smaller bundles before tying the knot. RESULTS: Field of vision and image brightness is adequate and allows the operator to suture with great precision and ease. Large angular movements of the 3 mm telescope should be made with its trocar. Image brightness depends on the proximity of the lens to the structure being inspected; it worsens when the lens is withdrawn even slightly. Reusable 3 mm instruments can be used hundreds of times and with care they have sufficient strength to permit tying tight even en-bloc ligatures of vascular bundles. Operating times are between 20 and 25 minutes, bilateral operations need about 10 minutes more. Wounds made by the 3 mm trocars are usually self-closing and rarely need to stitch. CONCLUSIONS: Many authors confirm that since we first described the technique 15 years ago laparoscopic varicocelectomy is a safe, quick and easy minimal invasive procedure, less expensive than open techniques or occlusion under radiological control. The Palomo retroperitoneal approach using en-bloc ligatures of the vascular pedicle laparoscopically shortens operative times, the percentage of failures is minimum and postoperative testicular volumes and sperm counts increase. The microlaparoscopic technique not only reduces surgical aggression, but also the risk of complications is less and it does not increase operative difficulty or operation time.

Equipment Design↗
PubMed1999

Midvastus approach in total knee arthroplasty: a description and a cadaveric study determining the distance of the popliteal artery from the patellar margin of the incision.

Total knee arthroplasty (TKA), one of the most efficacious procedures in orthopedics, requires complete exposure of the knee joint for precise instrumentation. Although most orthopedic surgeons agree that TKA is easily performed using a medial parapatellar approach, a large segment of the patellar blood flow is disrupted by this exposure. The southern or subvastus approach addresses these concerns; however, the procedure has the disadvantage of inadequate exposure in certain patients. A compromise between these two approaches, a midvastus approach, has been described. To decrease potential neurovascular injury, this cadaveric study of the midvastus approach determines the proximity of the incision to the popliteal vascular bundle and addresses the innervation pattern of the vastus medialis oblique. A midvastus arthrotomy was performed on 19 female and 15 male adult cadaveric knees. The midpoint of the superior pole of the patella and the superomedial patellar prominence were marked. After determining the midpoint between the 2 previously mentioned landmarks, an incision was made from that point paralleling the fibers of the vastus medialis oblique medially to the popliteal vascular bundle. The length of the incision was measured three times using calipers; measurements were averaged for each individual specimen, then by gender, and, finally, overall. Ninety-five percent confidence intervals were determined. Differences were assessed by an independent t-test with an alpha level of significance at .05. In addition, the terminal branches of the femoral nerve innervating the vastus medialis oblique were dissected in 5 cadavers. The femoral nerve branched extensively to innervate the vastus medialis oblique. The average distance between the patella and the popliteal vessels was 8.8 +/- 1.4 cm. The average distance in males, 9.5 +/- 1.4 cm, was significantly greater than the distance in females, 8.3 +/- 1.2 cm (P < .02). The distance appeared proportionate to the size of the extremity. The midvastus approach is a viable alternative for primary TKA in selected patients who are not obese and who have not had previous arthrotomy or osteotomy. The average distance (8.8 cm) and corresponding range (6.5 cm minimum to 12.3 cm maximum) are sufficient to suggest a maximal safe distance for sharp dissection of 4.5 cm from the patellar margin in an adult. For additional exposure, the muscle can be safely split further with blunt dissection.

Adult↗
PubMed2000

New instrumentation for video-assisted anterior spine release.

Endoscopic surgery in the area of orthopedics has been evolving, particularly in spine surgery. We describe the clinical outcome of thoracoscopic anterior spine release using new instruments. A harmonic scalpel (HS) with a 5-mm hook dissector was used to dissect the spine and rib and to coagulate and transect the vascular bundles. A rib dissector and resector were used for excision of the rib to be implanted in the disk spaces. We treated scoliosis in four patients (three male, one female) with a mean age of 19.5 +/- 4.5 years and thoracolumbar kyphosis in a 16-year-old male patient. A mean number of 6.5 +/- 2.5 vertebrae with scoliosis and four vertebrae with kyphosis were released. In all cases, division of the vascular bundle and exposure of the spine were completed using only the HS, and excision of a rib segment was performed via a port incision using only the rib dissector and resector. The mean duration of thoracoscopic anterior release was 92 +/- 28 min. Blood loss was minimal during and after surgery. Thoracoscopic anterior spine release can be facilitated by the new instruments described above.

Adolescent↗
PubMed1975

[The subcutaneous vascular system (lower extremity): studies on micro-preparations].

At the level of fascial penetration the cutaneous arteries of the lower extremity are constantly accompanied by 1 or 2 communicating veins of varying diameter. Usually, they penetrate the fascia in rows via the muscular interstitium. There they give up branches to the fascial vascular network, to pre- and subfascial areolar tissue and possibly to the muscle origins on the fascia, or to the intermuscular septa. The texture of the fascia itself determines the structure of fascial openings for the cutaneous vessels. In the subcutaneous tissue the arteries are accompanied by 1 or 2 veins (Vv. comitantes). Numerous arterio-arterial and intervenous anastomoses form a subcutaneous network of vascular bundles. Two anastomosing venous systems can be distinguished in the subcutis: The small Vv. comitantes are fed primarily by the subcutaneous adipose lobes, and end in communicating veins or flow into the subcutaneous veins (epifascial veins). These large subcutaneous veins on the other hand are responsible for the actual outflow from the venous network of the cutis. They form the saphenous system or empty into larger communicating veins. Between the subcutaneous arterioles and accompanying venules there are numerous capillary webs. In addition direct capillaries and looped as well as meandering or knotted arterio-venous shunts are found. The subcutaneous vascular bundles are fixed by a connective tissue. There are often typical capillary meshes within arterial sheat, oriented like a rope-ladder. They undergo prenatal development. The subcutaneous (epifascial) veins are surrounded by areolar tissue on the cutaneous as well as on the fascial side. Fibers from the accompanying connective tissue criss-cross into the adventitia and thereby anchor the veins in a movable fashion. Typical vascular patches with plane capillary networks characterize the areolar tissue around the subcutaneous veins, which is differentiating at the 2nd half of the fetal period. Within are also capillary loops and convoluted arterio-venous shunts.

Adult↗
PubMed2002

Ultrastructural localization of ATPase in mature tracheary elements of rice (Oryza sativa L.) stamen.

The development of mature tracheary elements (TEs) of rice (Oryza sativa L. cv. Nongkeng 58s-SD) stamen from big-vacuole to trinucleate pollen stage was studied with lead phosphate--deposition technique. At big-vacuole pollen stage, mature TEs, both in filament and connective, were short of ATPase activity. However, ATPase activity appeared at binucleate pollen stage; in filament, one or two vascular bundle cell (s) next to TE degenerated earlier than the rest; and the plasma membrane of degenerating cell (DC) always exhibited high ATPase activity on condition that the adjoining TE was of fully stretched second wall; when the second wall only turned up far off DC, the plasma membrane of DC still showed high ATPase activity except on borderline between DC and TE; in connective at the same stage, TEs also exhibited high ATPase activity, but the vascular bundle cell(s) adjoining TEs degenerated much later than their counterparts in filament. At trinucleate pollen stage, materials, either with or without ATPase activity, were observed both in filament and connective TEs. The above results indicated that (some of the) materials in mature TEs come from filament DC.

Adenosine Triphosphatases↗