scholarly journals STUDIES ON THE ENDOPLASMIC RETICULUM

1957 ◽  
Vol 3 (2) ◽  
pp. 269-300 ◽  
Author(s):  
Keith R. Porter ◽  
George E. Palade
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Muscle Contraction ◽  
Striated Muscle ◽  
Cell Types ◽  
Entire System ◽  
Structural Components ◽  
Reticular Structure ◽  
Vacuolar System

Several types of striated muscle have been examined by the technics of electron microscopy and the findings in myotome fibers of Amblystoma larvae, the sartorius, and cardiac muscle of the rat are reported on in some detail. Particular attention has been given to structural components of the interfibrillar sarcoplasm and most especially to a finely divided, vacuolar system known as the sarcoplasmic reticulum. This consists of membrane-limited vesicles, tubules, and cisternae associated in a continuous reticular structure which forms lace-like sleeves around the myofibrils. It shows a definable organization which repeats with each sarcomere of the fiber so that the entire system is segmented in phase with the striations of the associated myofibrils. Details of these repetitive patterns are presented diagrammatically in Text-figs. 1, 2, and 3 on pages 279, 283, and 288 respectively. The system is continuous across the fiber at the H band level and largely discontinuous longitudinally because of interruptions in the structure at the I and Z band levels. The structure of the system relates it to the endoplasmic reticulum of other cell types. The precise morphological relation of the reticulum to the myofibrils, with specializations opposite the different bands, prompts the supposition that the system is functionally important in muscle contraction. In this regard it is proposed that the membrane limiting the system is polarized like the sarcolemma and that the corresponding potential difference is utilized in the intracellular distribution of the excitatory impulse.

scholarly journals THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

1956 ◽  
Vol 2 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Keith R. Porter
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Constant Width ◽  
Muscle Cells ◽  
Cell Types ◽  
Thin Sections ◽  
System A ◽  
Structural Relationships ◽  
Complex Membrane

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

scholarly journals "Reticular" and "Areticular" Nissl Bodies in Sympathetic Neurons of a Lizard

1959 ◽  
Vol 6 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Stuart W. Smith
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sympathetic Neurons ◽  
Sympathetic Ganglia ◽  
Thin Sections ◽  
Phrynosoma Cornutum ◽  
Reticular Structure ◽  
Before And After ◽  
Partial Dispersion ◽  
Nissl Substance

Sympathetic ganglia of the horned lizard, Phrynosoma cornutum, were fixed in OsO4 and imbedded in methacrylate. Thin sections were cut for electron microscopy. Some adjacent thick sections were cut for light microscopy and were stained in acidified, dilute thionine both before and after digestion by RNase. In the light microscope two types of Nissl bodies are found, both removable by RNase: (1) a deep, diffuse, indistinctly bounded, metachromatic variety, and (2) a superficial, dense, sharply delimited, orthochromatic sort. Electron microscopically, the former ("reticular" Nissl bodies) corresponds to the granulated endoplasmic reticular structure of Nissl material previously described by others, whereas the latter ("areticular" Nissl bodies) comprises compact masses of particles of varying internal density and devoid of elements of endoplasmic reticulum. The constituent particles of the areticular Nissl material are 4 to 8 x the diameter of single ribonucleoprotein granules of the reticular Nissl substance and seem, near zones of junction with the reticular type, to arise by clustering of such granules with subsequent partial dispersion of the substance of the granules into an added, less dense material. It is suggested that the observed orthochromasia of the areticular Nissl substance is due to accumulation of a large amount of protein bound to RNA and, further, that these Nissl bodies may represent storage depots of RNA and protein.

Ultrastrucure of Peruvian and Aleutian Mummified Tissues

1980 ◽  
Vol 38 ◽  
pp. 528-529
Author(s):  
E.R. Rivera ◽  
E.A. Coughlin
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Striated Muscle ◽  
Cytoplasmic Organelles ◽  
Low Viscosity

Electron microscopy has been employed in the study of Egyptian and Aleutian human mumified tissues (1,2). The Egyptian mummification process apparently fixed some tissues well enough to allow observation of some cytoplasmic organelles (1). In observed Aleutian tissues, nucleoli and possibly endoplasmic reticulum have been found in cartilage but not in other tissues (2). The use of TEM methods may provide some indication of the preservation procedure during mummification. Arm muscle and pleura from Peruvian and Aleutian mummies were cut into 1 mm cubes and floated in 5% glutaraldehyde in 0.075 M PIPES buffer for 2 weeks at 4°C. This procedure allowed rehydration of tissue and fixation to proceed simultaneously. These tissues were then post-fixed in 2% OsQ4 and embedded in Spurr’s low viscosity resin (3) and sectioned for TEM. Functional human striated muscle and pleura were similarly prepared as controls.

scholarly journals THE LOCALIZATION OF CHOLINESTERASE ACTIVITY IN RAT CARDIAC MUSCLE BY ELECTRON MICROSCOPY

1964 ◽  
Vol 23 (2) ◽  
pp. 217-232 ◽  
Author(s):  
Morris J. Karnovsky
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Enzymatic Activity ◽  
Cardiac Muscle ◽  
Heart Muscle ◽  
Cholinesterase Activity ◽  
Physiological Role ◽  
Ultrastructural Level ◽  
Formalin Fixed

A method has been developed for localizing sites of cholinesterase activity in rat cardiac muscle by electron microscopy. The method utilizes thiocholine esters as substrates, and is believed to be dependent on the reduction of ferricyanide to ferrocyanide by thiocholine released by enzymatic activity. The ferrocyanide thus formed is captured by copper to form fine, electron-opaque deposits of copper ferrocyanide, which sharply delineate sites of enzymatic activity at the ultrastructural level. Cholinesterase activity in formalin-fixed heart muscle was localized: (a) in longitudinal elements of the sarcoplasmic reticulum, but not in the T, or transverse, elements; and (b) in the A band, with virtually no activity noted in the M band, or in the H zone. The I band was also negative. No activity was detected in the sarcolemma, or in invaginations of the sarcolemma at the level of the Z band. The perinuclear element of the sarcoplasmic (endoplasmic) reticulum was frequently strongly positive. Activity at all sites was completely abolished by omitting the substrates, or by inhibition with eserine 10-4 M and diisopropylfluorophosphate 10-5 M. Eserine 10-5 M completely inhibited reaction in the sarcoplasmic reticulum, and virtually abolished that in the A band. These observations, together with the use of the relatively specific substrates and suitable controls to eliminate non-enzymatic staining, indicate that cholinesterase activity was being demonstrated. The activity in rat heart against different substrates was that of non-specific cholinesterases, in accordance with biochemical data. The activity in the A band was considered to be probably due to myosincholinesterase. It is proposed that the localization of cholinesterases in myocardium at the ultrastructural level should be taken into account in considering the possible functions of these myocardial enzymes, and it is hoped that knowledge of their localization will open up new avenues of approach in considering their physiological role in myocardium, which at present is not definitely known.

scholarly journals OBLIQUELY STRIATED MUSCLE

1968 ◽  
Vol 36 (1) ◽  
pp. 245-259 ◽  
Author(s):  
Jack Rosenbluth
Keyword(s):  
Electron Microscopy ◽  
Sarcoplasmic Reticulum ◽  
Connective Tissue ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Body Muscle ◽  
Dense Bodies ◽  
Thick Filaments ◽  
Predominant Type ◽  
Physiological Differences

Body muscle cells of the bloodworm Glycera, a polychaete annelid, were studied by electron microscopy and compared with muscle cells of the more slowly acting nematode Ascaris, which have been described previously. Both muscles are obliquely striated. The predominant type of bloodworm fiber is characterized by a prominent transversely oriented sarcoplasmic reticulum with numerous dyads at the surface of each cell. Thick myofilaments are ∼3 µ long and overlap along ∼60% of their length in extended fibers and ∼80% in shortened fibers. There is virtually no endomysium and very little intracellular skeleton, and the cells are attached by desmosomes to one another rather than to connective tissue. Dense bodies are absent from the fibers and in their place are Z lines, which are truly linear rather than planar. Scattered among the predominant fibers are others, less orderly in arrangement, in which the SR is much less prominent and in which the thick filaments are thicker and longer and overlap to an even smaller degree. It is suggested that physiological differences between bloodworm and Ascaris muscles derive from differences in the proportion of series to parallel linkages between the contractile elements, differences in the amount and disposition of the SR, and differences in the impedance to shear within the myofibrils.

scholarly journals Release of Ca2+ from a non-mitochondrial store site in peritoneal macrophages treated with saponin by inositol 1,4,5-trisphosphate

1984 ◽  
Vol 223 (1) ◽  
pp. 229-236 ◽  
Author(s):  
M Hirata ◽  
E Suematsu ◽  
T Hashimoto ◽  
T Hamachi ◽  
T Koga
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Inhibitory Effect ◽  
Peritoneal Macrophages ◽  
Erythrocyte Ghosts ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Intracellular Store ◽  
Inositol 1,4,5 Trisphosphate ◽  
Inside Out

The effects of inositol 1,4,5-trisphosphate, prepared from human erythrocyte ghosts, on Ca2+ release from intracellular store sites were studied in saponin-treated guinea pig peritoneal macrophages. Micromolar concentrations of inositol 1,4,5-trisphosphate released Ca2+ within 1 min from store sites which had accumulated Ca2+ in the presence of 10 mM-NaN3. In the presence of 10 mM-NaN3, the Ca2+ accumulated in the presence of oxalate was seen in the endoplasmic reticulum of saponin-treated macrophages by electron microscopy, indicating that the site of Ca2+ released by inositol 1,4,5-trisphosphate may be endoplasmic reticulum-like membranes. When the concentrations of free Ca2+ were over 3.5 × 10(-6) M, the release of Ca2+ by this agent was inhibited. This inhibition may be due to either the higher concentration of extra-vesicular free Ca2+ or the larger accumulation of Ca2+ into the store site or perhaps both effects. MgCl2 also had an inhibitory effect on the Ca2+ release. Inositol 1,4,5-trisphosphate also released Ca2+ from cardiac sarcoplasmic reticulum, but not from erythrocyte inside-out vesicles.

scholarly journals LOCALIZATION OF ANTIBODIES BY ELECTRON MICROSCOPY IN DEVELOPING ANTIBODY-PRODUCING CELLS

1965 ◽  
Vol 26 (3) ◽  
pp. 759-778 ◽  
Author(s):  
S. de Petris ◽  
Gioanna Karlsbad
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Cells ◽  
Early Stage ◽  
Cell Types ◽  
Antibody Synthesis ◽  
Booster Injection ◽  
Perinuclear Space ◽  
Lymph Node Cells ◽  
Antigen Antibody

The development of antibody-producing cells in the early stages of the secondary or hyperimmune response has been studied with the electron microscope in lymph nodes of adult chinchilla rabbits immunized with ferritin or apoferritin. The intracellular distribution of antiferritin antibodies was determined in the lymph node cells at 1 to 5 days after a booster injection, employing the labelling technique previously used by the authors (12) to demonstrate the localization of antibodies in mature plasma cells. Antibodies were first detected at 48 hours in blasts; i.e., cells which have a poorly developed endoplasmic reticulum and a cytoplasm filled with many ribosomes grouped in clusters. The label was subsequently found in forms intermediate between blasts and plasma cells (plasmoblasts, immature plasma cells), in which the endoplasmic reticulum appeared progressively more developed. Antiferritin antibodies were also found in cells in mitosis. In all the above cell types, antigen-antibody precipitates were consistently found in the perinuclear space and in the cisternae of the granular endoplasmic reticulum, from an early stage in the development of the latter. Evidence was also obtained for the presence of antibody in the Golgi area. The results are discussed in relation to the possible cellular sites of antibody synthesis.

Ganglioneuromas in the Adrenal Medulla of F344 Rats

1980 ◽  
Vol 17 (5) ◽  
pp. 614-621 ◽  
Author(s):  
G. Reznik ◽  
J. M. Ward ◽  
H. Reznik-Schüller
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Ganglion Cells ◽  
Cell Types ◽  
Neurosecretory Granules ◽  
Supporting Cells ◽  
Clear Cut ◽  
Almost All ◽  
F344 Rats ◽  
Nissl Substance

Of 60,048 aging F344 rats, 28 had ganglioneuromas of the adrenal gland. The rats were between 58 and 122 weeks old; 25 of them between 93 and 122 weeks when the tumors were found. The neoplasms were composed of large or small typical ganglion cells with a large pale nucleus and a prominent, often eccentric, nucleolus. The ganglion cells usually were distributed throughout the medullary tumor and surrounded by various numbers of supporting cells, including Schwann's cell types, and capsular or satellite cells. Often there was no clear-cut border between ganglion cells and neoplastic pheochromocytes. Electron microscopy of re-embedded tissues showed neurosecretory granules and cytoplasmic areas with an extensive rough endoplasmic reticulum (Nissl substance) in the ganglion cells and axons. The Schwann's cells were surrounded by a basement membrane and formed long cytoplasmic extensions around the axons. Almost all ganglioneuromas were associated with neoplastic pheochromocytes which usually were located at the edge of the tumors.

scholarly journals THE SARCOPLASMIC RETICULUM OF STRIATED MUSCLE OF A CYCLOPOID COPEPOD

1963 ◽  
Vol 17 (3) ◽  
pp. 629-640 ◽  
Author(s):  
Wolf H. Fahrenbach
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Sarcoplasmic Reticulum ◽  
Striated Muscle ◽  
Cyclopoid Copepod ◽  
Dense Network ◽  
Abdominal Musculature ◽  
Contraction Speed ◽  
Tubular System ◽  
Fast Acting

The fine structure of the abdominal musculature of the copepod Macrocyclops albidus was investigated by electron microscopy. Tubules penetrate into the muscle fibers from the sarcolemma, continuity between the wall of the tubules and the sarcolemma being clear. A dense network of tubules envelops the myofibrils, its interstices being occupied by cisternal elements. At the Z lines the tubules traverse the interior of myofibrils, giving off branches which course longitudinally within the substance of the myofibrils. These branches are also accompanied by elongate, non-intercommunicating cisternae. Comparison of this fast acting copepod muscle with other vertebrate and invertebrate muscles indicates that the complexity of the tubular system is a function of the myofibrillar geometry, whereas the degree of development of the cisternal system is related to the contraction speed of the muscle.

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