Condensed tannins in sainfoin. 1. A histological and cytological survey of plant tissues

1993 ◽  
Vol 71 (9) ◽  
pp. 1147-1152 ◽  
Author(s):  
G. L. Lees ◽  
N. H. Suttill ◽  
M. Y. Gruber
Keyword(s):  
Electron Microscopy ◽  
Condensed Tannins ◽  
Condensed Tannin ◽  
Plant Tissues ◽  
Onobrychis Viciifolia ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Large Numbers ◽  
Fine Localization ◽  
Cellular Organelles

Sainfoin (Onobrychis viciifolia Scop.) organs and tissues were surveyed for the presence of proanthocyanidins or condensed tannin (CT) in an attempt to learn more about CT formation. Three histological methods were used: a vanillin–HCl stain to localize areas of CT formation through a distinctive cherry-red coloration of CT-containing cells; osmium fixation to further localize CT formation in cellular organelles using light microscopy; and fine localization and examination using electron microscopy. Cells containing CTs were found in relatively large numbers throughout the sainfoin plant in all organs except the roots. No CTs were found in the cotyledons or in some petals. Ultrastructural studies revealed that CTs are restricted to the vacuoles and appear to accumulate on the inner periphery adjacent to the tonoplast or in the centre of the organelle, possibly next to vacuolar invaginations. Key words: condensed tannin, proanthocyanidin, sainfoin, histology, transmission electron microscopy.

Condensed tannins in sainfoin. II. Occurrence and changes during leaf development

1995 ◽  
Vol 73 (10) ◽  
pp. 1540-1547 ◽  
Author(s):  
G. L. Lees ◽  
M. Y. Gruber ◽  
N. H. Suttill
Keyword(s):  
Electron Microscopy ◽  
Leaf Development ◽  
Condensed Tannins ◽  
Histological Study ◽  
Condensed Tannin ◽  
Light And Electron Microscopy ◽  
Leaf Primordia ◽  
Tissue Samples ◽  
Onobrychis Viciifolia ◽  
Mature Phase

A histological study examined condensed tannin (CT) formation in plant tissue samples taken from the meristematic area of very young sainfoin (Onobrychis viciifolia Scop.) seedlings and from leaflets sampled at various stages of development in mature plants growing in the greenhouse. Light and electron microscopy revealed no CT in the seedling meristem and leaf primordia, but CTs were seen very early in leaf development forming first in the vacuoles of discrete cells of the abaxial subepidermal layer when the leaflets were recognizable, but still folded. Immature leaflets collected from the growing point of a mature sainfoin plant show similar CT formation with the abaxial cell vacuoles filled with CT when the new leaves have reached the 90°-fold stage. As the leaflets unfold and mature, CTs begin to appear in the vacuoles of small, but discrete cells in the adaxial subepidermal layer while the tannin-containing cells in the abaxial subepidermal layer begin to lose CT. The CT continues to increase in the adaxial layer until typical enlarged tannin idioblasts or sacs are observed at full leaflet expansion and maturity. By this stage, the vacuoles in the abaxial layer are almost empty. In senescing leaflet samples collected from the leaf rachis attached to the last and second to last node near the base of the plant, the cells in both subepidermal layers have lost the majority of the CT that was originally formed. At senescence all tannin-containing cells appear as empty shells. We speculate that a finite amount of CT is formed in the two subepidermal layers of new leaves at different stages of early leaf development, does not increase during the mature phase, and is catabolized in older leaves and during senescence. Key words: condensed tannins, sainfoin, Onobrychis viciifolia, leaf development.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques

1975 ◽  
Vol 33 ◽  
pp. 556-557
Author(s):  
M. K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Carbon Films ◽  
Photographic Recording ◽  
Transmission Electron ◽  
Thin Carbon ◽  
The Common ◽  
Scanning Electron ◽  
Better Than ◽  
Cellular Organelles

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.

Ultrastructural studies of the relationship between actin filaments and secretory granules

1990 ◽  
Vol 48 (3) ◽  
pp. 458-459
Author(s):  
Ellen Holm Nielsen
Keyword(s):  
Electron Microscopy ◽  
Colloidal Gold ◽  
Actin Filaments ◽  
Secretory Granules ◽  
Secretory Cells ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Granule Membrane ◽  
Ultrathin Sections ◽  
Lowicryl K4m

In secretory cells a dense and complex network of actin filaments is seen in the subplasmalemmal space attached to the cell membrane. During exocytosis this network is undergoing a rearrangement facilitating access of granules to plasma membrane in order that fusion of the membranes can take place. A filamentous network related to secretory granules has been reported, but its structural organization and composition have not been examined, although this network may be important for exocytosis.Samples of peritoneal mast cells were frozen at -70°C and thawed at 4°C in order to rupture the cells in such a gentle way that the granule membrane is still intact. Unruptured and ruptured cells were fixed in 2% paraformaldehyde and 0.075% glutaraldehyde, dehydrated in ethanol. For TEM (transmission electron microscopy) cells were embedded in Lowicryl K4M at -35°C and for SEM (scanning electron microscopy) they were placed on copper blocks, critical point dried and coated. For immunoelectron microscopy ultrathin sections were incubated with monoclonal anti-actin and colloidal gold labelled IgM. Ruptured cells were also placed on cover glasses, prefixed, and incubated with anti-actin and colloidal gold labelled IgM.

Morphology and ultrastructure of oral strains of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

1980 ◽  
Vol 30 (2) ◽  
pp. 588-600
Author(s):  
S C Holt ◽  
A C Tanner ◽  
S S Socransky
Keyword(s):  
Electron Microscopy ◽  
Ruthenium Red ◽  
Actinobacillus Actinomycetemcomitans ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Large Numbers ◽  
Haemophilus Aphrophilus ◽  
Ruthenium Red Staining ◽  
Amorphous Surface ◽  
Scanning Electron

Selected human oral and nonoral strains of the genera Actinobacillus and Haemophilus were examined by transmission and scanning electron microscopy. The strains examined were morphologically identical to recognized Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Haemophilus paraphrophilus. By transmission electron microscopy, the cells were typically gram negative in morphology, with several strains possessing some extracellular ruthenium red-staining polymeric material. Numerous vesicular structures, morphologically identical to lipopolysaccharide vesicles, were seen to originate from and be continuous with the surface of the outer membrane. Large numbers of these vesicles were also found in the external environment. Scanning electron microscopic observations revealed that both actinobacilli and haemophili possessed surface projections and an amorphous surface material which connected and covered adjacent cells.

Re-evaluation of merogony of a Cystoisospora ohioensis-like coccidian and its distinction from gametogony in the intestine of a naturally infected dog

Parasitology ◽  
2019 ◽  
Vol 146 (6) ◽  
pp. 740-745
Author(s):  
J. P. Dubey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Developmental Stages ◽  
Surface Epithelium ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Sexual Stages ◽  
Endogenous Stages ◽  
Study Development

AbstractFour species of Cystoisospora, C. canis, C. ohioensis, C. neorivolta and C. burrowsi are described from feces of dogs. Of these, the oocysts of C. canis are the largest and easily distinguished from the remaining three species. Oocysts of C. ohioensis, C. neorivolta and C. burrowsi are difficult to distinguish because of overlap in their sizes. However, based on endogenous developmental stages, C. ohioensis is distinct from C. neorivolta and C. burrowsi because its endogenous stages are confined to surface epithelium of intestine whereas endogenous stages of C. neorivolta and C. burrowsi are predominantly in the lamina propria. There are uncertainties regarding the endogenous stages of C. neorivolta and C. burrowsi and there is no way now to determine whether C. burrowsi and C. neorivolta are different parasites; therefore, these are referred as C. ohioensis-like organisms. Additionally, mode of division of asexual stages of coccidia of dogs is largely unknown and ultrastructural studies are lacking. In the present study, development of asexual and sexual stages of a C. ohioensis-like organism in a naturally infected dog is described by light microscopy and by transmission electron microscopy. Merozoites divided by endodyogeny/merogony. Meronts were crescent/merozoite-shaped and contained a maximum of eight nuclei. A distinctive feature of merozoites was the presence of many PAS-positive amylopectin granules that were absent or rare in immature microgamonts making it possible to distinguish them.

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