Electron microscopic studies on developing cartilage

Development ◽  
1970 ◽  
Vol 23 (1) ◽  
pp. 169-184
Author(s):  
S. C. Goel
Keyword(s):  
Chondroitin Sulphate ◽  
Soluble Form ◽  
Ground Substance ◽  
Noncollagenous Proteins ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Acid Mucopolysaccharides ◽  
Microscopic Studies ◽  
Extracellular Materials ◽  
Cellular Organelles

The present communication describes the changing developmental pattern of the cellular organelles concerned with the synthesis and transfer of the extracellular materials during the process of chondrogenesis in chick limb-buds. Cartilage consists of a large amount of extracellular phase interspersed with chondrocytes. Chemically it is well established (Eastoe, 1961) that the main constituents of the extracellular phase are collagen and protein-polysaccharides. The latter are made up of a non-collagenous protein and acid mucopolysaccharides. The acid mucopolysaccharides are chondroitin sulphate A and C (Godman & Porter, 1960; Jackson, 1964). In electron micrographs, the extracellular phase is seen as an amorphous electron-translucent ground substance interlaced by fibrous material overlaid with electron-dense granules. The chemical interpretation of this ultrastructure is still dubious (Matukas, Panner & Orbison, 1967). It is usually considered that the amorphous ground substance consists of the acid mucopolysaccharides, the noncollagenous proteins and tropocollagen, which is a soluble form of collagen (Godman & Porter, 1960).

scholarly journals Proteoglycans of hyaline cartilage: Electron-microscopic studies on isolated molecules

1975 ◽  
Vol 151 (1) ◽  
pp. 157-166 ◽  
Author(s):  
J Thyberg ◽  
S Lohmander ◽  
D Heinegård
Keyword(s):  
Hyaline Cartilage ◽  
Chondroitin Sulphate ◽  
Costal Cartilage ◽  
Side Chain ◽  
Gel Chromatography ◽  
Electron Microscopic ◽  
The Core ◽  
Central Filament ◽  
Microscopic Studies ◽  
Chondroitin Sulphate Chain

Proteoglycan monomers from guinea-pig costal cartilage, bovine nasal and bovine tracheal cartilage were observed in the electron microscope after being spread in a monomolecular layer with cytochrome c. The proteoglycan molecule appeared as an extended central core filament to which side-chain filaments were attached at various intervals. The molecules from the three sources displayed great ultrastructural similarities. On average, the core filament was about 290 nm long, there were about 25 side-chain filaments per core filament, the side-chain filaments were about 45 nm long, and the distance between the attachment points of the side-chain filaments to the core filament was about 11 nm. With regard to the overall size of the molecules, no evidence of distinct subpopulations was obtained. Good correlation was found between ultrastructural data for the proteoglycan molecules and chemical data obtained by enzyme digestions and gel chromatography. Together these data strongly support the interpretation of the electron-microscopic pictures as indicating a central filament corresponding to the protein core and side-chain filaments corresponding to the chondroitin sulphate chain clusters of the proteoglycan monomers.

scholarly journals EFFECT OF ACTIVE ACCUMULATION OF CALCIUM AND PHOSPHATE IONS ON THE STRUCTURE OF RAT LIVER MITOCHONDRIA

1964 ◽  
Vol 23 (1) ◽  
pp. 21-38 ◽  
Author(s):  
John W. Greenawalt ◽  
Carlo S. Rossi ◽  
Albert L. Lehninger
Keyword(s):  
Specific Gravity ◽  
Rat Liver ◽  
Cesium Chloride ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Phosphate Ions ◽  
Microscopic Studies

Rat liver mitochondria allowed to accumulate maximal amounts of Ca++ and HPO4= ions from the suspending medium in vitro during respiration have a considerably higher specific gravity than normal mitochondria and may be easily separated from the latter by isopycnic centrifugation in density gradients of sucrose or cesium chloride. When the mitochondria are allowed to accumulate less than maximal amounts of Ca++ and HPO4= from the medium, they have intermediate specific gravities which are roughly proportional to their content of calcium phosphate. Maximally "loaded" mitochondria are relatively homogeneous with respect to specific gravity. Correlated biochemical and electron microscopic studies show that Ca++-loaded mitochondria contain numerous dense granules, of which some 85 per cent are over 500 A in diameter. These granules are electron-opaque not only following fixation and staining with heavy metal reagents, but also following fixation with formaldehyde, demonstrating that the characteristic granules in Ca++-loaded mitochondria have intrinsic electron-opacity. The dense granules are almost always located within the inner compartment of the mitochondria and not in the space between the inner and outer membranes. They are frequently located at or near the cristae and they often show electron-transparent "cores." Such granules appear to be made up of clusters of smaller dense particles, but preliminary x-ray diffraction analysis and electron diffraction studies have revealed no evidence of crystallinity in the deposits. The electron-opaque granules decrease in number when the Ca++-loaded mitochondria are incubated with 2,4-dinitrophenol; simultaneously there is discharge of Ca++ and phosphate from the mitochondria into the medium.

ATP is required in platelet serotonin exocytosis for protein phosphorylation and priming of secretory vesicles docked on the plasma membrane

1996 ◽  
Vol 109 (1) ◽  
pp. 113-118
Author(s):  
T. Morimoto ◽  
S. Ogihara
Keyword(s):  
Plasma Membrane ◽  
Protein Phosphatase ◽  
Secretory Activity ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Granule Membrane ◽  
Microscopic Studies ◽  
Amorphous Structures ◽  
Gamma S

Calcium-evoked secretion generally requires the presence of millimolar concentrations of Mg-ATP. We investigated the role of Mg-ATP in the secretion of serotonin from electropermeabilized bovine platelets. The secretion of serotonin was lost within 5 minutes when the Mg-ATP concentration was diluted to less than 0.1 mM, but was maintained when ATP-gamma S (adenosine 5′-O-3-thiotriphosphate) was used instead of ATP. Okadaic acid, a potent inhibitor of protein phosphatase, could also maintain the exocytotic activity even when ATP was diluted. Decrease in the secretory activity was paralleled by a decrease in phosphorylation level of four proteins after dilution of ATP, but the activity was maintained when the thiophosphorylation level of these proteins was maintained. Two of these proteins were digested by a protease, calpain, which has been shown to lead to a loss in the exocytotic activity. Electron microscopic studies showed that calcium did not induce the formation of distinct bridge-like structures between the granule membrane and the plasma membrane in Mg-ATP-diluted cells, previously shown as the structure transiently formed prior to fusion of the two membranes. Anchorage of the secretory dense granules to the plasma membrane and the presence of the amorphous structures between the granules and the plasma membrane were unchanged by dilution of ATP. These results indicate that ATP is not required for the anchorage itself, but is required to prime anchored granules for calcium-triggered secretion. Maintenance of the phosphorylated state of proteins by ATP enables the calcium trigger to form the bridge-like structures preceding membrane fusion events.

Light and Electron Microscopic Studies of the Seminal Vesicular Glands of the African Straw-coloured Fruit Bat, Eidolon helvum

2020 ◽  
Author(s):  
C.N. Abiaezute ◽  
I.C. Nwaogu ◽  
I.R. Obidike ◽  
U.M. Igwebuike
Keyword(s):  
Abiotic Factors ◽  
Secretory Cells ◽  
Basal Cells ◽  
Reproductive Structure ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Fruit Bat ◽  
Microscopic Studies ◽  
Eidolon Helvum ◽  
Near Threatened

Background: Secretions from the seminal vesicular gland enhance the survival and reproductive functions of the spermatozoa. The order Chiroptera has evolved great diversity in their reproductive structure influenced by location, abiotic factors and availability of food. Eidolon helvum is a near threatened tropical African fruit bat and little is known of its reproductive biology. The aim of this study was to highlight the structure, histochemistry and ultrastructure of the seminal vesicular glands of Eidolon helvum. Methods: The paired seminal vesicular glands of 16 adult male Eidolon helvum were obtained in May during the early rainy season in tropical Nigeria. The glands were evaluated grossly, histological and ultrastructurally.Result: The spirally coiled tubular organs were divided into numerous lobules of tubular-alveolar glandular acini lined by simple cuboidal epithelium made up of basal cells and mono or bi-nucleated cuboidal secretory cells. PAS positive secretions projected from the apical surfaces. Principal secretory cells contained numerous rough endoplasmic reticulum, mitochondria, Golgi complexes, electron lucid secretory vesicles, electron dense granules and lysosomes. The unique merocrine and apocrine secretions contributed to the formation of vaginal plugs.

Ultrastructural Characteristics of Kaposi's Sarcoma

1967 ◽  
Vol 53 (4) ◽  
pp. 379-413 ◽  
Author(s):  
Vincenzo Bàrbera ◽  
Luigi Mazzarella
Keyword(s):  
Kaposi's Sarcoma ◽  
Membrane Vesicles ◽  
Kaposi’S Sarcoma ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Spindle Cells ◽  
Cytoplasmic Filaments ◽  
Microscopic Studies ◽  
Ultrastructural Characteristics ◽  
Characteristic Features

The uncertainty which exists on the histogenesis of Kaposi's sarcoma is emphasized and the pertinent literature is briefly reviewed, with particular reference to electron microscopic studies. The results of an investigation on the fine structure in 6 cases of the disease are presented and the characteristic features of the two principal types of cellular elements, endothelial-like and spindle cells, are described. The relevant aspects observed were a clearly outlined basement membrane, vesicles due to pinocytosis, dense granules presumably due to erythrophagocytosis and, most interesting because it had never been recognized before, the presence of cytoplasmic filaments 90–110 Å thick, which show considerable variation in number, distribution, course and direction. These filaments appear to be similar to those that have been shown in endothelial cells and seem structurally identical to leiomyofilaments. In discussing the significance of these findings, a correlation is made with the results of previously reported electron microscopic studies and the hypothesis is postulated that the tissue of Kaposi's sarcoma originates from mesenchymatous elements which may develop into cells either of the endothelial-like and of the leiomuscular-like type.

scholarly journals Electron Microscopic Studies of Dense Granules in Lutein Cells of Pregnant Rats

1982 ◽  
Vol 53 (8) ◽  
pp. 579-581
Author(s):  
Tetsuya KOHSAKA ◽  
Sueo NIIMURA ◽  
Kazuo ISHIDA
Keyword(s):  
Electron Microscopic ◽  
Pregnant Rats ◽  
Dense Granules ◽  
Microscopic Studies

Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland

1978 ◽  
Vol 36 (2) ◽  
pp. 46-47
Author(s):  
Jan Zarzycki ◽  
Joseph Szroeder
Keyword(s):  
Mammary Gland ◽  
Protein Denaturation ◽  
Chemical Constituents ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Mouse Mammary Gland ◽  
Electron Microscopic ◽  
Preparation Methods ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.

Early Development of Drug-Induced Hepatic Necrosis

1971 ◽  
Vol 29 ◽  
pp. 576-577
Author(s):  
F. G. Zaki ◽  
E. Detzi ◽  
C. H. Keysser
Keyword(s):  
Early Development ◽  
Hepatic Necrosis ◽  
Screening Tests ◽  
Dense Matrix ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Hepatocellular Damage ◽  
Sprague Dawley Rats ◽  
Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

Electron Microscopic identification of Pre-B Lymphocytes in the Bone Marrow of a Patient with Chronic Myelocytic Leukemic in Blast Crisis

1982 ◽  
Vol 40 ◽  
pp. 346-347
Author(s):  
T. Mullin ◽  
G. Yee ◽  
M. Aheam ◽  
J. Trujillo
Keyword(s):  
Blast Crisis ◽  
Immunoglobulin M ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Transformation Theory ◽  
Electron Microscopic ◽  
Chemotherapeutic Sensitivity ◽  
Microscopic Studies ◽  
Hematopoietic Precursor ◽  
Lymphoblastic Transformation ◽  
B Lineage

There have been numerous reports in the current literature suggesting that hematopoietic precursor cells in some human chronic myelocytic leukemias (CML) undergo lymphoblastic transformation at the time of the acute blast crisis (BC) stage. The primary evidence offered in support of this transformation theory--lymphoblastic appearing morphology, increased terminal deoxynucleotidyl transferase (TdT) activity, and chemotherapeutic sensitivity to vincristine and prednisone--has been indirect, however, since these features may occur in nonlymphoid cells. More direct support for the Pre-B lineage of these cells has recently been provided by immunofluorescent light microscopic studies demonstrating the presence of intracytoplasmic immunoglobulin M (IgM) in these CML-BC cells.

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