scholarly journals CYTOPLASMIC MICROTUBULE AND WALL MICROFIBRIL ORIENTATION IN ROOT HAIRS OF RADISH

1965 ◽  
Vol 27 (3) ◽  
pp. 575-589 ◽  
Author(s):  
Eldon H. Newcomb ◽  
Howard T. Bonnett
Keyword(s):  
Osmium Tetroxide ◽  
Root Hairs ◽  
Uranyl Acetate ◽  
Cellulose Microfibrils ◽  
Wall Structure ◽  
Root Tips ◽  
Cytoplasmic Microtubule ◽  
Thin Sections ◽  
Oriented Layer

The fine structure of young root hairs of radish was studied, with special attention to cytoplasm-wall relationships. Hairs up to 130 µ in length were examined after fixation of root tips in glutaraldehyde followed by osmium tetroxide. Microtubules occur axially aligned in the cytoplasm just beneath the plasmalemma, and extend from the base of the hair to within 2 to 3 µ of the tip. Poststaining with uranyl acetate and lead citrate clearly reveals in thin sections the presence of the two layers of cellulose microfibrils known from studies on shadowed wall preparations: an outer layer of randomly arranged microfibrils arising at the tip, and a layer of axially oriented microfibrils deposited on the inside of this layer along the sides. The youngest microfibrils of the inner, oriented layer first appear at a distance of about 25 µ from the tip. Although the microfibrils of the inner layer and the adjacent microtubules are similarly oriented, the oriented microtubules also extend through the 20- to 25-µ zone near the tip where the wall structure consists of random microfibrils. This suggests that the role of microtubules in wall deposition or orientation may be indirect.

scholarly journals An Electron Microscopic Investigation into the Effect of EDTA on Plant Cell Wall

1960 ◽  
Vol 7 (2) ◽  
pp. 335-338 ◽  
Author(s):  
Shimon Klein ◽  
B. Ginzburg
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Microscopic Investigation ◽  
Uranyl Acetate ◽  
Electron Microscopic Investigation ◽  
Wall Structure ◽  
Acetate Solution ◽  
Root Tips ◽  
Electron Microscopic ◽  
Thin Sections

To study the effect of EDTA on cell wall structure and the reversal of this effect by uranyl ion, thin sections of pea root tips were examined in the electron microscope. EDTA is known to facilitate separation of the cells in root tips. When sections of fixed and embedded EDTA-treated roots are floated on a uranyl-acetate solution, a loose network is revealed that would seem to be cellulose. Incorporation of uranyl into the roots, if it occurs prior to fixation, brings about recementation of the cells. After such treatment, a marginal darker area and a median brighter one can be observed in the wall, and the whole structure appears more compact again. Comparison of the results of the various treatments suggests that cellulose-cementing material is dispersed throughout the entire wall, and that its distribution parallels that of cellulose.

Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

1978 ◽  
Vol 36 (2) ◽  
pp. 628-629
Author(s):  
C. N. Sun ◽  
C. Araoz ◽  
H. J. White
Keyword(s):  
Nuclear Envelope ◽  
Tumor Cells ◽  
Osmium Tetroxide ◽  
Primitive Neuroectodermal Tumor ◽  
Uranyl Acetate ◽  
Neuroectodermal Tumor ◽  
Annulate Lamellae ◽  
Lead Citrate ◽  
Thin Sections ◽  
The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

Ultrastructure of myoepithelial cell in parotid gland

1988 ◽  
Vol 46 ◽  
pp. 342-343
Author(s):  
C. N. Sun
Keyword(s):  
Parotid Gland ◽  
Osmium Tetroxide ◽  
Individual Cell ◽  
Branching Processes ◽  
Muscle Cells ◽  
Myoepithelial Cells ◽  
Uranyl Acetate ◽  
Thin Sections ◽  
Gland Carcinoma ◽  
Parotid Gland Carcinoma

Myoepithelial cells have been observed in the prostate, harderian, apocrine, exocrine sweat and mammary glands. Such cells and their numerous branching processes form basket-like structures around the glandular acini. Their shapes are quite different from structures seen either in spindleshaped smooth muscle cells or skeletal muscle cells. These myoepithelial cells lie on the epithelial side of the basement membrane in the glands. This presentation describes the ultrastructure of such myoepithelial cells which have been found also in the parotid gland carcinoma from a 45-year old patient.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4 percent glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. Ultrastructurally, the pattern of each individual cell showed wide variations.

Observations of thick and thin sections in a field-emission SEM

1994 ◽  
Vol 52 ◽  
pp. 1018-1019
Author(s):  
W. P. Wergin ◽  
S. Roy ◽  
E. F. Erbe ◽  
C. A. Murphy ◽  
C. D. Pooley
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Thin Sections ◽  
Transmission Electron ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

Larvae of the nematode, Steinernema carpocapsae Weiser strain All, were cryofixed and freezesubstituted for 3 days in acetone containing 2% osmium tetroxide according to established procedures. Following chemical fixation, the nematodes were brought to room temperature, embedded in Spurr's medium and sectioned for observation with a Hitachi S-4100 field emission scanning electron microscope that was equipped with an Oxford CT 1500 Cryotrans System. Thin sections, about 80 nm thick, similar to those generally used in conventional transmission electron microscope (TEM) studies were mounted on copper grids and stained with uranyl acetate for 30 min and lead citrate for 5 min. Sections about 2 μm thick were also mounted and stained in a similar fashion. The grids were mounted on an Oxford grid holder, inserted into the microscope and onto a cryostage that was operated at ambient temperature. Thick and thin sections of the larvae were evaluated and photographed in the SEM at different accelerating voltages. Figs. 4 and 5 have undergone contrast conversion so that the images would resemble transmitted electron micrographs obtained with a TEM.

scholarly journals Role of PBP1 in Cell Division of Staphylococcus aureus

2007 ◽  
Vol 189 (9) ◽  
pp. 3525-3531 ◽  
Author(s):  
S. F. F. Pereira ◽  
A. O. Henriques ◽  
M. G. Pinho ◽  
H. de Lencastre ◽  
A. Tomasz
Keyword(s):  
Cell Division ◽  
Cell Mass ◽  
Nile Red ◽  
Inducible Promoter ◽  
Wall Structure ◽  
Intact Cells ◽  
Thin Sections ◽  
Methicillin Resistant ◽  
Essential Function

ABSTRACT We constructed a conditional mutant of pbpA in which transcription of the gene was placed under the control of an IPTG (isopropyl-β-d-thiogalactopyranoside)-inducible promoter in order to explore the role of PBP1 in growth, cell wall structure, and cell division. A methicillin-resistant strain and an isogenic methicillin-susceptible strain, each carrying the pbpA mutation, were unable to grow in the absence of the inducer. Conditional mutants of pbpA transferred into IPTG-free medium underwent a four- to fivefold increase in cell mass, which was not accompanied by a proportional increase in viable titer. Examination of thin sections of such cells by transmission electron microscopy or fluorescence microscopy of intact cells with Nile red-stained membranes showed a morphologically heterogeneous population of bacteria with abnormally increased sizes, distorted axial ratios, and a deficit in the number of cells with completed septa. Immunofluorescence with an antibody specific for PBP1 localized the protein to sites of cell division. No alteration in the composition of peptidoglycan was detectable in pbpA conditional mutants grown in the presence of a suboptimal concentration of IPTG, which severely restricted the rate of growth, and the essential function of PBP1 could not be replaced by PBP2A present in methicillin-resistant cells. These observations suggest that PBP1 is not a major contributor to the cross-linking of peptidoglycan and that its essential function must be intimately integrated into the mechanism of cell division.

scholarly journals Supra-physiological levels of Gibberellins/DELLAs alter the patterning, morphology and abundance of root hairs in root tips of A. thaliana seedlings

2021 ◽  
Author(s):  
Iva McCarthy-Suarez
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Epidermal Cell ◽  
Root Hair ◽  
Root Hairs ◽  
Root Tip ◽  
Spatial Patterning ◽  
Root Tips ◽  
Root Epidermis

In spite of the known role of gibberellins (GAs), and of their antagonistic proteins, the DELLAs, in leaf hair production, no investigations, however, have assessed their hypothetical function in the production of root hairs. To this aim, the effects of supra-physiological levels of GAs/DELLAs on the spatial patterning of gene expression of the root hair (CPC) and root non-hair (GL2, EGL3 and WER) epidermal cell fate markers, as well as on the distribution, morphology and abundance of root hairs, were studied in root tips of 5-day-old A. thaliana seedlings. Results showed that excessive levels of GAs/DELLAs impaired the spatial patterning of gene expression of the root hair/non-hair epidermal cell fate markers, as well as the arrangement, shape and frequency of root hairs, giving rise to ectopic hairs and ectopic non-hairs, two-haired cells, two-tipped hairs, branched hairs, longer and denser hairs near the root tip under excessive DELLAs, and shorter and scarcer hairs near the root tip under excessive GAs. However, when the gai-1 (GA-insensitive-1) DELLA mutant protein was specifically over-expressed at the root epidermis, no changes in the patterning or abundance of root hairs occurred. Thus, these results suggest that, in seedlings of A. thaliana, the GAs/DELLAs might have a role in regulating the patterning, morphology and abundance of root hairs by acting from the sub-epidermal tissues of the root.

An Electron Microscopic Investigation of the Pathogenesis of Hemorrhage Induced by Rattlesnake Venom

1974 ◽  
Vol 32 ◽  
pp. 56-57
Author(s):  
Charlotte L. Ownby ◽  
Robert A. Kainer ◽  
Anthony T. Tu
Keyword(s):  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Microscopic Investigation ◽  
Uranyl Acetate ◽  
Electron Microscopic Investigation ◽  
Lead Citrate ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Rattlesnake Venom ◽  
Diamondback Rattlesnake

One of the significant changes induced by the injection of rattlesnake (Crotalidae) venom is hemorrhage. Since crotaline antivenin does not prevent such local tissue damage, a more effective treatment of snakebite is needed. To aid in the development of such a treatment the pathogenesis of venom-induced hemorrhae was investigated.Swiss-Webster white mice were injected intramuscularly with Western diamondback rattlesnake (Crotalus atrox) venom. Two minutes after the injection, muscle tissue was obtained by bioosy from the thigh and fixed in 6% glutaraldehyde in Milloniq's phosphate buffer (DH 7.4, 2 hrs., 4°C). After post-fixation in 2% osmium tetroxide in Milloniq's phosphate buffer (pH 7.4, 1hr., 4°C) the tissue was dehydrated routinely in ethanol and embedded in Epon 812. The thin sections were stained with uranyl acetate in methanol and lead citrate then observed with either a Zeiss EM 9A or an Hitachi HS-8 electron microscope.

Ultrastructure of Granules Passing Through Frog Oocyte Nuclear Pores

1969 ◽  
Vol 27 ◽  
pp. 288-289
Author(s):  
Madison B. Cole
Keyword(s):  
Osmium Tetroxide ◽  
Rana Pipiens ◽  
Uranyl Acetate ◽  
Nuclear Pores ◽  
Thin Sections ◽  
Close Proximity ◽  
Perinuclear Cytoplasm ◽  
Frog Oocyte ◽  
Pass Through ◽  
Number Of Authors

Ovaries of Rana pipiens larvae were fixed in glutaraldehyde, post-fixed in osmium tetroxide, and embedded in epon. Thin sections of oocytes were routinely stained using methanolic uranyl acetate followed by lead citrate.The granule, designated M1, found in the primary oocytes is considered to pass through the nuclear pores by virtue of 1) its location in the nucleoplasm in close proximity to the nuclear envelope, 2) its contact with the nuclear pores, 3) its presence in aggregates in the perinuclear cytoplasm and A) its similarity to granules referred to by a number of authors (1-4) as material passing through nuclear pores.

Electron Microscopy as an aid to diagnosis in pediatric hematology/oncology

1989 ◽  
Vol 47 ◽  
pp. 1062-1063
Author(s):  
K. L. Saving ◽  
R. C. Caughey
Keyword(s):  
Electron Microscopy ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
En Bloc ◽  
Thin Sections ◽  
Megakaryoblastic Leukemia ◽  
Pediatric Hematology ◽  
Transmission Electron ◽  
Microscopy Techniques

This presentation is designed to demonstrate how scanning and transmission electron microscopy techniques can be utilized to confirm or support a variety of unusual pediatric hematologic/oncologic disorders. Patients with the following diagnoses will be presented: (1) hereditary pyropoikilocytosis, (2) familial erythrophagocytic lymphohistiocytosis, (3) acute megakaryoblastic leukemia, and (4) pseudo-von Willebrand’s disease.All transmission and scanning electron microscopy samples were fixed in 2.5% glutaraldehyde, rinsed in Millonig’s phosphate buffer, and post-fixed with 1% osmium tetroxide. The transmission samples were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole ’ s non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin. Ultramicrotomy thin sections were stained with uranyl acetate and lead citrate and scanned using a JEOL-JEM 100C, The scanning samples were dehydrated with graded series of ethanols, critical point dried with CO2, gold-coated, and scanned using a JEOL-JSM 35. The peroxidase samples were fixed in 3% glutaraldehyde, incubated in diaminobenzidine (DAB), dehydrated with ethanol, embedded with Epon 812, and scanned without post-staining using a JEOL-JEM 100C.

Comparative study of ultrastructure of HIV and SIV

1990 ◽  
Vol 48 (3) ◽  
pp. 342-343
Author(s):  
Takashi Nakano ◽  
Shunro Imura ◽  
Masuyo Nakai
Keyword(s):  
Osmium Tetroxide ◽  
Staining Method ◽  
Culture Fluid ◽  
Ultrastructural Feature ◽  
Uranyl Acetate ◽  
Negative Staining ◽  
Thin Sections ◽  
Viral Particles ◽  
Infected Cells ◽  
Hiv 1

The ultrastructural feature of AIDS viruses (HIV and SIV) was observed by ultrathin-sectioning and negative staining method, and the surface structures of these viruses were compared.HIV-1 group including, HTLV-III and LAV-1 were used. And in HIV-2 group, LAV-2, which was isolated from a Senegalese AIDS patient, and GH-1, which was isolated from a Ghanan AIDS patient, were used. SIV group was used AGM-1, which was isolated from an African green monkey. The virions were used which was produced from Molt-4 cells after the infection of each viruses of these strains. The infected cells and viral particles, which were collected by centrifugation were fixed with 2% glutaraldehyde (GA), washed with PBS, and postfixed with 1% osmium tetroxide. The specimens were dehydrated in graded ethanol, and embedded in Epon 812. The thin sections were stained with uranyl acetate and lead citrate. On the other hand, for negative staining, 25% GA was added to the supernatant culture fluid and finally concentrated on 2% GA. Then virions were collected by ultracentrifugation.

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