Fine structure of intercellular junctions and blood vessels in medulloblastomas

1975 ◽  
Vol 33 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Jacques Hassoun ◽  
Asao Hirano ◽  
Harry M. Zimmerman
Keyword(s):  
Fine Structure ◽  
Blood Vessels ◽  
Intercellular Junctions

The fine structure of blood vessels in chromophobe adenoma

1972 ◽  
Vol 22 (3) ◽  
pp. 200-207 ◽  
Author(s):  
Asao Hirano ◽  
Uwamie Tomiyasu ◽  
H. M. Zimmerman
Keyword(s):  
Fine Structure ◽  
Blood Vessels ◽  
Chromophobe Adenoma

Fine structure of psammoma bodies at the outer aspect of blood vessels in meningioma

1985 ◽  
Vol 66 (2) ◽  
pp. 163-166 ◽  
Author(s):  
T. Kubota ◽  
A. Hirano ◽  
K. Sato ◽  
S. Yamamoto
Keyword(s):  
Fine Structure ◽  
Blood Vessels ◽  
Psammoma Bodies ◽  
Outer Aspect

Studies on the fine structure of invertebrate blood vessels

1976 ◽  
Vol 172 (3) ◽  
pp. 405-423 ◽  
Author(s):  
Frithjof Hammersen ◽  
Hans-Walter Staudte ◽  
Elke M�hring
Keyword(s):  
Fine Structure ◽  
Blood Vessels

The fine structure of neurons and other elements in the nervous system of the giant African land snail Archachatina marginata

1964 ◽  
Vol 160 (979) ◽  
pp. 167-180 ◽  
Keyword(s):  
Fine Structure ◽  
Blood Vessels ◽  
Glial Cells ◽  
Golgi Complex ◽  
Land Snail ◽  
Interstitial Cells ◽  
Muscle Fibres ◽  
Nerve Fibres ◽  
Dense Granules ◽  
Sheath Cells

Much of the fine structure of the neurons, interstitial cells, blood vessels, collagen, and muscle fibres resembles that of similar elements in other species. In this preliminary report attention is paid to those features which characterize the structure of the neurons and interstitial cells. Within each group there are morphologically distinct cell types. The giant neurons (> 100 /un) are distinguished from smaller neurons by the irregular shapes of their nuclei, and by the extensive penetration of their perikarya by processes of surrounding sheath cells. A substance having a structure similar to that of glycogen is present both in the sheath cells and in the neuronal cytoplasm . The sheath cells may, therefore, be functioning as ‘nurse’ cells. The sheath cells form one group of interstitial cells. Two other groups are defined in accordance with their spatial relationships to the neurons. The glial cells are distributed between the sheath cells, where they may form a mass of glial tissue, and they are present in the walls of the blood vessels. The cytoplasm is extended into processes and in the region of the nucleus appears to be extremely active. It is characterized particularly by an abundance of the Golgi complex, small granular and large laminated electron-dense inclusions, and the particulate substance which may be glycogen. Structures which resemble the electron-dense inclusions of glial cells are found in the cytoplasm of neurons. The third group of interstitial cells consists of supporting cells which surround nerve fibres. Large fibres and particularly the neurite are deeply penetrated by these cells and the phenomenon appears to be associated with the formation of collateral nerve fibres. Dense fibrils permeate the cytoplasm and desmosomes are present between the cells, which, therefore, appear to form a resilient framework around the nerve fibres. Nerve fibres in the neuropil and nerves contain a complex array of vesicular and granular inclusions. These comprise small clear vesicles (350 to 600 A), electron-dense granules (600 to 2000 A) and a range of granular vesicles which have a structure intermediate in character betweenth at of the clear vesicles and the dense granules. The dense granules in the nerve fibres are identical with those which are present in the perikarya and which have their origin in the cisternae of the Golgi complex. A dense substance accumulates between the membranes and is concentrated in the form of a granule towards one end of a cisterna, from which it is pinched off by constriction of the mem­branes. This is probably the origin of the granules which collect in the nerve fibres. The vesicular and granular elements in the fibres are never completely segregated, although clusters occur in which one type predominates. Occasionally, in regions where the clear vesicles are prevalent, these may be associated with a thickened membrane which is apposed to a similar thickening of an adjacent nerve fibre. The whole structure closely resembles synapses which have been described in other animals. The nature of the substances located in the vesicles and granules has not been determined.

scholarly journals STUDIES ON INFLAMMATION

1961 ◽  
Vol 11 (3) ◽  
pp. 571-605 ◽  
Author(s):  
G. Majno ◽  
G. E. Palade
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Blood Vessels ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Intercellular Junctions ◽  
Supporting Evidence ◽  
Electron Microscopic ◽  
Tracer Particles

The mechanism, whereby histamine and serotonin increase the permeability of blood vessels, was studied in the rat by means of the electron microscope. The drugs were injected subcutaneously into the scrotum, whence they diffused into the underlying (striated) cremaster muscle. An intravenous injection of colloidal HgS was also given, in order to facilitate the identification of leaks by means of visible tracer particles. After intervals varying from 1 minute to 57 days the animals were killed; the cremaster was fixed, embedded in methacrylate, and examined with the electron microscope. One to 12 minutes after the injection, the blood vessels of the smallest caliber (3 to 5 micra as measured on electron micrographs) appeared intact. Numerous endothelial openings were present in blood vessels with a diameter of 7 to 8 micra or more. These gaps were 0.1 to 0.8 micra in width; portions of intercellular junctions were often present in one or both of the margins. The underlying basement membrane was morphologically intact. An accumulation of tracer particles and chylomicra against the basement membrane indicated that the latter behaved as a filter, allowing fluid to escape but retaining and concentrating suspended particulate matter of the size used. Uptake of tracer particles by endothelial vesicles was minimal. Phagocytosis by endothelial cells became more prominent at 3 hours, but as a secondary occurrence; the pericytes were actively phagocytic at all stages. At the 3-hour stage no leaks were found. The changes induced by histamine and serotonin were indistinguishable, except that the latter was more potent on a mole-to-mole basis. In control animals only small accumulations of tracer particles were found in the wall of a number of blood vessels. With regard to the pathogenesis of the endothelial leaks, the electron microscopic findings suggested that the endothelial cells become partially disconnected along the intercellular junctions. Supporting evidence was provided at the level of the light microscope, by demonstrating—in the same preparation—the leaks with appropriate tracer particles1, and the intercellular junctions by the silver nitrate method. The lipid nature of the chylomicron deposits observed in electron micrographs was also confirmed at the level of the light microscope, using cremasters fixed in formalin and stained in toto with sudan red.

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