The epicuticle of a marine isopod, Idotea baltica (Pallas)

1980 ◽  
Vol 58 (2) ◽  
pp. 305-308 ◽  
Author(s):  
K. Halcrow
Keyword(s):  
Dense Matrix ◽  
Central Layer ◽  
Outermost Layer ◽  
Idotea Baltica ◽  
Innermost Layer ◽  
Cylindrical Cavities ◽  
Electron Dense Matrix

An unusually elaborate epicuticle is described in Idotea baltica. The bulk of the epicuticle consists of a central tightly packed array of irregularly cylindrical cavities arranged perpendicularly within an electron-dense matrix. The latter is continuous with material composing a layer on each side of the central layer. The outermost layer contains vesicles the lumina of which are seen frequently to open to the outside. Similar vesicles are seen within the central layer, and at the junction of this layer and the innermost layer of the epicuticle. The latter is the narrowest of the three regions and bears abundant small projections where it contacts the outermost region of the exocuticle.

Liver ultrastructure in sheep fasciolosis

2021 ◽  
Vol 1 (1) ◽  
pp. 6-12
Author(s):  
V. N. Baymatov ◽  
◽  
G. R. Shakirova ◽  
Keyword(s):  
Experimental Infection ◽  
Ultrastructural Level ◽  
Dense Matrix ◽  
Membrane Structures ◽  
Liver Ultrastructure ◽  
Perinuclear Space ◽  
Liver Membrane ◽  
Electron Dense Matrix ◽  
Anthelmintic Drugs

This experiment has studied the changes in the liver in sheep during experimental infection with fascioliasis. Sheep were infested with 300 adoliskaria and observed changes up to 142 days. At the ultrastructural level in animals with fascioliasis, destructive changes were found in the liver. In the nucleus, the number of nucleoli decreases or they disappear completely, fragmentation of heterochromatin occurs and the content of euchromatin increases. The karyolemma exfoliates from the nucleus, as a result of which the perinuclear space expands. Mitochondria swell, they are polymorphic, and have an electron-dense matrix. At the beginning of the invasion, their number increases, and then their vacuolization, destruction occurs, while under the action of anthelmintic drugs and fasciolus toxins, the structure of the endolasmic network first of all changes: its cavities expand, then fragmentation occurs. Ribosomes are sprayed into the cytoplasm of the hepatocyte. It should be noted that under the influence of hexichol, acemidophene and thiopagol in the liver, membrane structures change most significantly and undergo necrobiosis.

An ultrastructural study of pollen development in tomato (Lycopersicon esculentum). I. Tetrad to early binucleate microspore stage

1993 ◽  
Vol 71 (8) ◽  
pp. 1039-1047 ◽  
Author(s):  
P. L. Polowick ◽  
V. K. Sawhney
Keyword(s):  
Endoplasmic Reticulum ◽  
Lycopersicon Esculentum ◽  
Ultrastructural Study ◽  
Pollen Development ◽  
Pollen Wall ◽  
Ultrastructural Changes ◽  
Dense Matrix ◽  
Tetrad Stage ◽  
Microspore Stage ◽  
Electron Dense Matrix

Microspores undergo considerable ultrastructural changes between the tetrad and early binucleate microspore stages of microsporogenesis in tomato (Lycopersicon esculentum). Pollen wall deposition began late in the tetrad stage, and by the early microspore stage a lamellar foot layer and tectum were deposited. Sculpturing of the tectum was evident by the early binucleate microspore stage. Dictyosomes and vesicles were abundant during the period of pollen wall formation. Plastids were associated with the endoplasmic reticulum (ER) to form plastid–ER complexes, from the late tetrad to the vacuolate microspore stage. At the vacuolate microspore stage, endoplasmic reticulum independent of plastids was also observed, and at the early binucleate microspore stage ER was not associated with plastids. Free ribosomes were evenly distributed throughout the cytoplasm until the vacuolate microspore stage when they were organized into polysomes. Mitochondria were spherical to ellipsoid, with an electron-dense matrix and swollen cristae, until the early binucleate microspore stage when they were highly elongate and became convoluted. Key words: Lycopersicon esculentum, microsporogenesis, pollen development, tetrads, tomato, ultrastructure.

scholarly journals IDENTIFICATION OF PEROXISOMES IN THE RAT ADRENAL CORTEX

1972 ◽  
Vol 20 (3) ◽  
pp. 173-179 ◽  
Author(s):  
MARGARET E. BEARD
Keyword(s):  
Acid Phosphatase ◽  
Adrenal Cortex ◽  
Zona Fasciculata ◽  
Positive Staining ◽  
Staining Reaction ◽  
Dense Matrix ◽  
Zona Reticularis ◽  
Liver And Kidney ◽  
Branched Structures ◽  
Electron Dense Matrix

Organelles with the ultrastructure and cytochemical characteristics of peroxisomes (microbodies) have been identified in cells of the zona fasciculata and zona reticularis of the rat adrenal cortex. These peroxisomes appear as small, elliptical to spherical or branched structures, enclosed by a single membrane and composed of a moderately electron-dense matrix. They do not possess a nucleoid or core of the type found in peroxisomes of liver and kidney. These organelles show a strongly positive staining reaction with the diaminobenzidine technique for peroxidatic activity of catalase. This staining is inhibited by aminotriazole. In cytochemical preparations revealing acid phosphatase activity, lysosomes are strongly stained and peroxisomes are free of reaction product.

Ultrastructure of conidium ontogeny in Phoma pomorum, Microsphaeropsis olivaceum, and Coniothyrium fuckelii

1976 ◽  
Vol 54 (9) ◽  
pp. 831-851 ◽  
Author(s):  
John P. Jones
Keyword(s):  
Electron Microscopy ◽  
Dense Matrix ◽  
Spore Dispersal ◽  
Electron Dense Matrix

The techniques of electron microscopy have been used to elucidate the details of conidium ontogeny in Phoma pomorum, Microsphaeropsis olivaceum, and Coniothyrium fuckelii. All three of these organisms were shown to be phialidic. The pyenidia of these organisms contained an electron-dense matrix, which in nature, probably functions as an aid to spore dispersal. In Phoma pomorum it was possible to trace conidia to their originating conidiophore through this matrix.

scholarly journals PEROXISOMES IN DORSAL ROOT GANGLIA

1973 ◽  
Vol 21 (1) ◽  
pp. 34-41 ◽  
Author(s):  
ELENA CITKOWITZ ◽  
ERIC HOLTZMAN
Keyword(s):  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Schwann Cells ◽  
Dorsal Root Ganglia ◽  
Acid Phosphatase Activity ◽  
Dorsal Root ◽  
Dense Matrix ◽  
Crystalline Core ◽  
Electron Dense Matrix

Bodies with the morphologic and cytochemical characteristics of peroxisomes have been identified in the satellite and Schwann cells of rat dorsal root ganglia. They are membrane-delimited, round or oval structures which contain a moderately electron-dense matrix but lack a crystalline core. On incubation of the tissue in a cytochemical medium for demonstration of peroxisomes, these bodies show heavy deposits of reaction product. The reaction is inhibited by heating the tissue or by incubation in the presence of aminotriazole or dichlorophenolindophenol. In tissue incubated for acid phosphatase activity the bodies are not reactive, although lysosomes show reaction product.

Fine structure of the anterior adhesive apparatus (head organs) of Bravohollisia gussevi Lim, 1995 (Monogenea: Ancyrocephalidae)

Parasitology ◽  
2005 ◽  
Vol 132 (3) ◽  
pp. 427-438 ◽  
Author(s):  
W. L. WONG ◽  
G. P. BRENNAN ◽  
D. W. HALTON ◽  
L. H. S. LIM
Keyword(s):  
Electron Microscopy ◽  
Gland Cell ◽  
Light And Electron Microscopy ◽  
Dense Matrix ◽  
General Body ◽  
Gland Cells ◽  
Transmission Electron ◽  
Similar Band ◽  
Electron Dense Matrix ◽  
Dense Vesicles

A study of the anterior adhesive apparatus (head organs) of Bravohollisia gussevi Lim, 1995 was carried out using light and electron microscopy. The anterior adhesive apparatus or head organs in B. gussevi comprise 6 circular openings or apertures in the antero-lateral region, associated pits lined with specialized microvillous tegument that differ from the general body tegument, a bundle of ducts, and uninucleate gland cells located lateral to the pharynx. The uninucleate glands of the anterior adhesive apparatus (head organs) comprise 2 types of cells, one kind of cell producing rod-like bodies (S1) and the other oval bodies (S2). The S1 bodies are filled with numerous, less electron-dense vesicles in an electron-dense matrix, while S2 bodies have no vesicles but contain a more homogeneous electron-dense matrix. Interlinking band-like structures were observed between S1 bodies. Similar band-like structures were found between S2 bodies. The formation of S1 bodies was followed by transmission electron microscopy. However, the formation of S2 bodies was unclear and could not be resolved. Uniciliated structures were also observed around the openings of the anterior adhesive apparatus. Each uniciliated structure is usually associated with an opening of a gland cell producing granular, electron-dense, secretory bodies, which differ from the secretions produced by the lateral gland cells of the anterior adhesive apparatus.

THE SECRETORY PATHWAY IN PLATELETS STUDIED BY CRYO-FIXATION

1987 ◽  
Author(s):  
E morqenstern ◽  
H Patscheke
Keyword(s):  
Osmium Tetroxide ◽  
Secretory Pathway ◽  
Freeze Substitution ◽  
Human Platelets ◽  
Dense Matrix ◽  
Compound Exocytosis ◽  
Ultrathin Sections ◽  
Granule Secretion ◽  
Large Compound ◽  
Electron Dense Matrix

It is widely held, that the constituents packed in the a -granules are released by stimulated platelets via the surface connected system (SCS). By means of the fast-freezing and freeze substitution technique (which allow the investigation of membrane fusion) we found a secretory pathway in platelets (compound exocytosis) without an involvement of the SCS during the release of a-granules. To study the process of a-granule secretion human platelets concentrated in citrated blood plasm were stimulated with thrombin or collagen. 20 - 120 seconds after stimulation the platelets were rapidly frozen with a metal-mirror attachment to the KF 80 cryofixation unit (REICHERT-JUNG). Using plastic spacers droplets of the PRP were slammed against a copper block at 80 K at a rate of 0.2 m/sec. After cryofixation the specimens were transferred (in liquid nitrogen) into a Cs-auto cryosubstitution unit (REICHERT-JUNG). Cryosubstitution was programmed for 48h at 193 K in acetone with 4% osmium tetroxide. The temperature went automatically up to room temperature at a rate of 10 K/h. The specimens were embedded in araldite. The analysis of serial ultrathin sections of platelets in different phases of exocytosis revealed the following. a -granules in apposition showed different stages of swelling and dispersal of their electron dense matrix. Membrane appositions were also found between a -granules. The contraction of a sphere of microfilaments and microtubules during stimulation seemed to support this process. On the other hand this internal contraction prevented most of the a-granules from contacting with the plasmalemma. We observed fusion between swollen -granules in apposition and the plasmalemma and swollen and unswollen a -granules. Thus, large compound granules were formed frequently before fusion of the secretory organelles with the plasmalemma took place. These observations suggested that a -granules in stimulated platelets performed a compound exocytosis after swelling. The process seemed to start with the apposition of a -granule membranes to the plasmalemma. It cannot yet be answered whether the swelling of the granules is due to an osmotically driven influx of water or due to an influx after microfusion.Supported by DFG, Grant Mo 124/2-4

The egg envelopes of Polymorphus minutus (Acanthocephala)

Parasitology ◽  
1973 ◽  
Vol 66 (3) ◽  
pp. 387-403 ◽  
Author(s):  
P. J. Whitpield
Keyword(s):  
Light And Electron Microscopy ◽  
Dense Matrix ◽  
Structural Protein ◽  
Egg Envelope ◽  
Inner Surface ◽  
Histochemical Evidence ◽  
Fertilization Membrane ◽  
Egg Envelopes ◽  
Electron Microscopical ◽  
Electron Dense Matrix

The series of egg envelopes around the acanthor in the mature egg of the palaeacanthocephalan, Polymorphus minutus, has been investigated with light and electron microscopy. An attempt has been made to characterize the macromolecules from which the envelopes are constructed using histochemistry, an analysis of stabilizing bond types and comparisons of envelope fine structure with that of other structural protein systems. The outermost envelope (I) of the mature Polymorphus egg is a fertilization membrane. It is produced by membrane-bounded inclusions in the cytoplasm of the unfertilized oocyte which discharge their contents into the extracellular space around the egg. Envelope II is composed largely of keratin, and its subzones consist of different packing arrangements of 8 nm diameter electron-lucid filaments in an electron-dense matrix. The electron microscopical appearances which this filamentous keratin can present due to section orientation artefacts are discussed. The innermost envelope (III) is 20–30 nm thick and highly corrugated. The spaces between envelopes I and II and between envelope III and the inner surface of envelope II contain material with a granular or fibrous ultrastructure. These spaces show histochemical evidence for the presence of acid mucopolysaccharides.

Cytochemical and enzymatic characterization of the sporulation septum of Streptomyces antibioticus

1981 ◽  
Vol 27 (10) ◽  
pp. 1060-1065 ◽  
Author(s):  
Alfredo F. Braña ◽  
Manuel B. Manzanal ◽  
Carlos Hardisson
Keyword(s):  
Enzymatic Digestion ◽  
Cross Linking ◽  
Dense Matrix ◽  
Enzymatic Characterization ◽  
Chemical Modifications ◽  
Streptomyces Antibioticus ◽  
Highly Sensitive ◽  
Thin Electron ◽  
Electron Dense Matrix

The sporulation septum in Streptomyces antibioticus is formed by two thin electron-dense layers which constitute the annuli, separated by a thick and moderately electron-dense matrix which forms the deposits. By means of cytochemical techniques and enzymatic digestion with lysozyme, we have shown that deposits and annuli have a different chemical composition. Deposits are formed by peptidoglycan and are highly sensitive to lysozyme, whereas annuli, probably due to localized chemical modifications of the peptidoglycan or high degrees of peptide cross-linking, are lysozyme resistant. Our results suggest that the deposits, unlike the annuli, are only temporary assisting structures which are degraded during spore maturation.

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