Sarcolemma, T-tubules, and subsarcolemmal caveolae. Interrelationships and continuity demonstrated by tannic acid mordanting

1978 ◽  
Vol 56 (3) ◽  
pp. 391-397 ◽  
Author(s):  
T. S. Leeson
Keyword(s):  
Electron Density ◽  
Tannic Acid ◽  
Basal Lamina ◽  
Extracellular Space ◽  
Lead Citrate ◽  
Single Row ◽  
Rectus Abdominus ◽  
Ultrathin Sections ◽  
T Tubules ◽  
Do So

Muscle cells of rat rectus abdominus and diaphragm were mordanted in tannic acid and ultrathin sections, after staining with lead citrate, showed a variable but usually marked increase in electron density of T-tubules, subsarcolemmal caveolae and, to a lesser degree, the plasmalemma, basal lamina material, and associated collagen microfibrils. The technique permits clear demonstration of continuity of the membranes of T-tubules and caveolae with the sarcolemma. While some T-tubules open directly into the extracellular space, others do so indirectly via a caveola. The T-tubules show some variation in diameter and not all are transverse in orientation; they frequently branch, reunite, and run longitudinally, often connecting T-tubules of adjacent triads across a Z-line. Subsarcolemmal caveolae (approximately 100 nm diameter) line the sarcolemma in a single row and show frequent connections by narrow tubules to form dumbell, trefoil, and four-leafed profiles.The findings lead to the conclusion that both T-tubules and caveolae are open to the extracellular space and that T-tubules open both directly and indirectly via caveolae to the surface.

The transverse tubular (T) system of rat cardiac muscle fibers as demonstrated by tannic acid mordanting

1978 ◽  
Vol 56 (9) ◽  
pp. 1906-1916 ◽  
Author(s):  
T. S. Leeson
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Tannic Acid ◽  
Extracellular Space ◽  
Inverse Relationship ◽  
Muscle Fibres ◽  
Fiber Size ◽  
T Tubules ◽  
Cardiac Muscle Fibers ◽  
T System

T-tubules and subsarcolemmal caveolae in rat cardiac muscle fibres have been studied using the tannic acid mordanting technique. While T-tubules form an extensive and relatively regular meshwork with triads at Z-lines in ventricular fibers, in atrial fibers the tubules are often absent, or very sparse and with an irregular distribution. There appears to be a relation to fiber size, the meshwork being more extensive in fibers of larger diameter, and an inverse relationship to the number of couplings found between sarcoplasmic reticulum and plasmalemma. In larger atrial fibers, while the T-tubule meshwork was extensive, it did not show the regularity of distribution found in ventricular fibers. T-tubule continuity with the extracellular space was visualized clearly, both directly and indirectly via subsarcolemmal caveolae.

The Identification of Phospholipid Micelles in Glutaraldehyde-Urea Embedded Tissue

1975 ◽  
Vol 33 ◽  
pp. 494-495
Author(s):  
Daniel C. Pease
Keyword(s):  
Electron Micrographs ◽  
Lung Tissue ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Type Ii ◽  
Lead Citrate ◽  
Phospholipid Micelles ◽  
Type Ii Pneumocytes ◽  
Ultrathin Sections ◽  
Polar Water

It is reasonable to think that phospholipid micelles should be visible and identifiable in electron micrographs of ultrathin sections if only they can be preserved throughout the embedding process. The development of highly polar, water-containing, aminoplastic embedments has made this a likely possibility. With this in mind, an investigation of the lecithin-secreting, Type II pneumocytes of the lung is underway.Initially it has been easiest to recognize phospholipid micelles in lung tissue fixed first with glutaraldehyde, and then secondarily exposed to osmium tetroxide. However, the latter is not a necessary concomitant for micellar preservation. Conventional uranyl acetate and lead citrate staining is finally applied. Importantly, though, the micelles have been most easily seen in tissue embedded in 507. glutaraldehyde polymerized with urea, as described in detail by D.C. Pease and R.G. Peterson (J. Ultra- struct. Res., 41, 133, 1972). When oriented appropriately, the micellar units are seen as tiny, bilayer plates.

Fine structural morphology of immunocytes of some molluscs and insects

1990 ◽  
Vol 48 (3) ◽  
pp. 386-387
Author(s):  
S.G. Pal ◽  
G. Baur ◽  
B. Ghosh ◽  
S. Palit ◽  
S. Modak ◽  
...  
Keyword(s):  
Blood Cells ◽  
Phosphate Buffer ◽  
Room Temperature ◽  
Structural Information ◽  
Uranyl Acetate ◽  
Meretrix Meretrix ◽  
Lead Citrate ◽  
Bivalve Molluscs ◽  
Structural Morphology ◽  
Ultrathin Sections

In recent years some of the blood cells of several molluscs and insects are characterised as immunocytes. Similar cells from a few invertebrates from India have been looked into under conventional TEM to register the ultrastructural features. This type of study is first of its kind in the subcontinent. Immunocytes from bivalve molluscs Meretrix meretrix, Laroellidens marqinalis and two insect species, apterygote Ctenolepism a longicaudata and pterygote Gesonula punctifrons provide a new set of fine structural information which forms a basis of comparison with those studied earlier.Immunocytes have been collected from the fresh live species of bivalve molluscs and insects obtained locally at Calcutta. These were fixed in icecold 2% glutaraldehyde in 0.1M phosphate buffer (pH 7.2-7.4) for 1-2 hours at 4-5°C. Subseguently pellets were post-osmicated in 1% OsO4 at room temperature for 1-2 hours. Following dehydration these were embedded in Araldite mixture in plastic capsules and polymerization was effected for 2 days at 60°C. Ultrathin sections were cut in a ultrotome and sections were double stained with Uranyl acetate and lead citrate. These were viewed in a TEM.

scholarly journals Redistribution of alpha-granules and their contents in thrombin-stimulated platelets.

1984 ◽  
Vol 98 (2) ◽  
pp. 748-760 ◽  
Author(s):  
P E Stenberg ◽  
M A Shuman ◽  
S P Levine ◽  
D F Bainton
Keyword(s):  
Plasma Membrane ◽  
Tannic Acid ◽  
Extracellular Space ◽  
Plasma Membranes ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Thin Sections ◽  
Immunocytochemical Techniques ◽  
Morphologic Changes ◽  
Stimulation Of

The redistribution of beta-thromboglobulin (beta TG), platelet Factor 4 (PF4), and fibrinogen from the alpha granules of the platelet after stimulation with thrombin was studied by morphologic and immunocytochemical techniques. The use of tannic acid stain and quick-freeze techniques revealed several thrombin-induced morphologic changes. First, the normally discoid platelet became rounder in form, with filopodia, and the granules clustered in its center. The granules then fused with one another and with elements of the surface-connected canalicular system (SCCS) to form large vacuoles in the center of the cell and near the periphery. Neither these vacuoles nor the alpha granules appeared to fuse with the plasma membrane, but the vacuoles were connected to the extracellular space by wide necks, presumably formed by enlargement of the narrow necks connecting the SCCS to the surface of the unstimulated cell. The presence of fibrinogen, beta TG, and PF4 in corresponding large intracellular vacuoles and along the platelet plasma membrane after thrombin stimulation was demonstrated by immunocytochemical techniques in saponin-permeabilized and nonpermeabilized platelets. Immunocytochemical labeling of the three proteins on frozen thin sections of thrombin-stimulated platelets confirmed these findings and showed that all three proteins reached the plasma membrane by the same pathway. We conclude that thrombin stimulation of platelets causes at least some of the fibrinogen, beta TG, and PF4 stored in their alpha granules to be redistributed to their plasma membranes by way of surface-connected vacuoles formed by fusion of the alpha granules with elements of the SCCS.

Branching morphogenesis in the avian lung: electron microscopic studies using cationic dyes

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 189-205
Author(s):  
Betty C. Gallagher
Keyword(s):  
Tannic Acid ◽  
Basal Lamina ◽  
Branching Morphogenesis ◽  
Ruthenium Red ◽  
Interparticle Spacing ◽  
Blue Staining ◽  
Mouse Lung ◽  
Alcian Blue Staining ◽  
Electron Microscopic ◽  
Avian Lung

The developing chick lung was examined in the electron microscope for intimate cell contacts between epithelium and mesenchyme, discontinuities in the basal lamina and substructure of the basement membrane. Cell filopodia were seen which crossed the basal lamina from both the epithelial and the mesenchymal cells. Ruthenium red and tannic acid staining of the basal lamina of the chick lung showed it to be thin and sometimes discontinuous at the tips compared to the more substantial basal lamina in the interbud areas. The bilaminar distribution of particles seen with ruthenium red is similar to those seen in the cornea and lens. With tannic acid staining, filaments could be seen which crossed the lamina lucida and connected with the lamina densa. Spikes perpendicular to the basal lamina were sometimes seen with a periodicity of approximately 110 nm. Alcian blue staining revealed structure similar to that seen by ruthenium red staining in the salivary and mammary glands, although the interparticle spacing was closer. Collagen was located in areas of morphogenetic stability, as has been seen by other investigators in different tissues. Collagen was coated with granules (probably proteoglycan) at periodic intervals when stained with ruthenium red. The fibrils were oriented circumferentially around the mesobronchus and were assumed to continue into the bud, but the fibres curve laterally at the middle of a bud. This orientation is opposite to that seen by another investigator in the mouse lung. In general, the observations made in the avian lung are similar to those seen in branching mammalian tissue. It is likely, therefore, that the chick lung uses strategies in its morphogenesis that are similar to those that have been elucidated previously in developing mammalian organs.

Ultrastructure of a sensillum associated with the pharynx of the cockroach Periplaneta americana

1996 ◽  
Vol 74 (11) ◽  
pp. 1999-2008
Author(s):  
R. Gary Chiang ◽  
K. G. Davey
Keyword(s):  
Electron Microscopy ◽  
Cell Body ◽  
Extracellular Space ◽  
Direct Contact ◽  
Periplaneta Americana ◽  
Sensory Cell ◽  
Sensory Cells ◽  
Osmotic Concentration ◽  
Sensory Cilia ◽  
Ultrathin Sections

A sensillum associated with the pharynx of the cockroach Periplaneta americana was examined in serial ultrathin sections using electron microscopy. This sensillum consisted of a group of 10–20 similar sensillar subunits. Each sensillar subunit possessed one 60- to 70-μm long dendritic sheath that made direct contact with the cuticle. The dendritic sheath enclosed 3–5 sensory cilia arising from 3–5 sensory cells located in a cluster approximately 30 μm proximal to the base of the sheath. Between the sensory cell body and the base of the sheath the dendrites were wrapped by the sheath-forming cell. Before entering the dendritic sheath itself, the dendrites crossed through an extracellular space, the ciliary sinus. No cuticular specializations, such as a well-defined sensory hair or pore, were observed. The structure of this sensillum suggests that it responds poorly to mechanical distortion of its surroundings. This characteristic supports the hypothesis that this sensillum measures the osmotic concentration of the ingested food.

Ultrastructure of the Epidermis and Protonephridium of an Undescribed Species of Luridae (Platyhelminthes, Rhabdocoela)

1993 ◽  
Vol 41 (4) ◽  
pp. 415 ◽  
Author(s):  
K Rohde ◽  
NA Watson ◽  
A Faubel
Keyword(s):  
Extracellular Matrix ◽  
Single Cell ◽  
Basal Lamina ◽  
Dense Material ◽  
Undescribed Species ◽  
Single Row ◽  
Longitudinal Ribs ◽  
Capillary Walls

The epidermis of an undescribed species of Luridae possesses many large cavities filled with a medium-dense material, intraepidermal nuclei, glandular ducts, cilia with vertical and horizontal rootlets, surface microvilli, and a thick basal lamina. Cilia have narrow tips, the peripheral axonemal doublets lose one of the microtubules and, finally, whole doublets are lost near the tip. Flame bulbs have a single row of longitudinal ribs containing microtubules and connected by a 'membrane' apparently of extracellular matrix; cilia of flame bulbs possess cross-striated rootlets, and capillary walls are smooth. The nucleus of the protonephridium was observed near the tip of the flame bulb, along the capillary. It is not clear whether one perikaryon forms more than one flame bulb. The structure of the epidermal ciliary rootlets, the presence of intraepidermal nuclei, and flame bulbs composed of a single row of longitudinal ribs containing microtubules formed by a single cell are typical rhabdocoel characteristics.

The fine structure of ascus development in Lasiobolus monascus (Pezizales)

1978 ◽  
Vol 56 (7) ◽  
pp. 862-872 ◽  
Author(s):  
James W. Kimbrough ◽  
Gerald L. Benny
Keyword(s):  
Fine Structure ◽  
Uranyl Acetate ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Stalk Cell ◽  
Lead Citrate ◽  
Electron Microscopic ◽  
Ultrathin Sections ◽  
Microscopic Inspection ◽  
Physical And Chemical

Ultrastructural and cytochemical studies on the ascus of Lasiobolus monascus are presented. Apothecia in various stages of development were obtained in culture and prepared for both light and electron microscopic observations. Ultrathin sections for electron microscopic inspection were often treated with silver methenamine to enhance wall characteristics. Ascus development was followed from fertilization to maturity.In this species, the ascogonium enlarges after fertilization to become the ascus mother cell. Two pores are present in the young ascus, one connecting it to the antheridium and another between the ascus and stalk cell. The ultrastructural features of these pores in the young and maturing ascus are described. During ascus enlargement, as many as four wall layers are found when poststained with silver methenamine. Only two layers are clearly distinguishable when poststained with uranyl acetate and lead citrate. The apical zone of dehiscence is characterized by a distinct annular swelling which appears during early ascosporogenesis. By spore maturation, this swelling is not evident either at the light or electron microscopic level. Instead, there appear to be both physical and chemical changes in the area of dehiscence. The wall is distinctly thinner and much more electron transparent in the area of dehiscence when treated with silver methanamine.

Electron Microscopic Study of a Spontaneous Rat Tumor

1971 ◽  
Vol 29 ◽  
pp. 322-323
Author(s):  
P. W. Cole ◽  
R. M. Jamison
Keyword(s):  
Propylene Oxide ◽  
Uranyl Acetate ◽  
Female Rat ◽  
Lead Citrate ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Non Invasive ◽  
Ultrathin Sections ◽  
Glass Knife ◽  
Rat Tumor

A spontaneously occurring, non-invasive mammary tumor was observed in a 7-month-old, non-lactating, random-bred Sprague-Dawley female rat. The tumor was located subcutaneously in the distal mammary line as a firmly encapsulated, lobated growth. The tumor was surgically removed and immersed in Clark's buffer containing 4% glutaraldehyde. (Later conventional histochemical studies revealed this tumor to be a relatively non-differentiated fibro-adenoma.) Exterior and interior portions of the tumor were excised and fixed separately. The tissues were cut into 1 mm cubes and fixed for 4 hours in 4% glutaraldehyde. The specimens were then washed 4 times in buffer and left overnight at 4°C in the buffer. The cubes were postfixed in 2% OsO4 for 2 hours, after which they were dehydrated in a graded series of ethanol. The specimens were then washed with 2 changes of propylene oxide and perfused with a 1:1 mixture of propylene oxide-Epon 812 for 1 hour. Next, the tissue cubes were embedded in a mixture of Epon 812, DDSA, NMA, and DMP 30. Polymerization was allowed to proceed sequentially at 37°C overnight, 45°C for 8 hours, and 60°C for 24 hours. Ultrathin sections were cut with the Porter-Blum MT-2B ultramicrotome equipped with a glass knife. Sections were picked up on copper grids and stained with saturated uranyl acetate and 0.2% lead citrate. Specimens were examined in the Philips 300 electron microscope at instrumental magnifications ranging from 3,000-20,000 times.

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