ISSN:0741-0581    

DOI:10.1002/jemt.1060120202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractNumber, length, and diameters of dendritic spines of the granule cell in the dorsal leaf of the rat dentate gyrus were measured by using high‐voltage electron microscope stereo images of 5‐m̈m‐thick Golgi preparations with the aid of a three‐dimensional image analyzer system.Spine densities of 2.02 ± 0.28, 2.28 ± 0.33, and 3.36± 0.35 per 1 μm at distal, middle, and proximal portions of the dendrite were obtained. These values were about 1.6‐fold of the previous light microscopical report.Mean three‐dimensional spine length were 1.244 ± 0.506 μm, 1.262 ± 0.563 μm, and 1.254 ± 0.584 μm at distal, middle, and proximal portions, respectively, which were about 1.4 times longer than those measured in two dimensions.By using measured morphometrical parameters of spines such as lengths, diameters, and population densities, total spine surface areas of 2.401 μm2, 2.806 μm2, and 4.180 μm2per 1 μm of the dendrite at distal, middle, and proximal portions, respectively, were obtained. The total surface area of dendrite was about doubled by the addition of the spines at each dendritic portion.The advantageous features and the problems of the pr

ISSN:0741-0581    

DOI:10.1002/jemt.1060120203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractTo examine the optimal preparatory procedures of cryofixation for immunocytochemistry, the labeling density over the antigenic sites in cells processed by various protocols of freeze‐substitution and embedding was quantitatively evaluated. Fresh tissue blocks of gerbil parotid gland were quickly frozen by a metal contact method using liquid helium and freezesubstituted with one of the following media: 4% OsO4in acetone or 0.4% OsO4in acetone or 0.3% glutaraldehyde in acetone. They were then embedded in either an Epon‐Araldite mixture or Araldite 6005, which were polymerized at 60°C and 50°C, respectively. Some frozen samples substituted with aldehyde‐containing acetone were embedded in Lowicryl K4M (polymerized at —30°C). Immunocytochemical localization of amylase was examined by indirect immunostaining by using antigerbil parotid amylase antibody and protein A/gold complex. Thin sections of epoxyresin‐embedded materials were treated with oxidizing agents before immunostaining. The central dense core of heterogeneous secretory granules in the acinar cells was heavily labeled with immunogold, regardless of substitution media and embedding resins employed. The labeling density on thin sections of all the cryofixed materials examined was about 1.5 times or more as high as in those processed by conventional chemical fixation. The highest value of the labeling density was obtained from material which was substituted with 0.3% glutaraldehyde in acetone and embedded in Araldite 6005. Substitution with osmium‐containing acetone appeared not to seriously affect immunoreactivity of the antigenic sites and was advantageous because of the distinctive images of membranes. Advantages and disadvantages of the individual protocols employed

ISSN:0741-0581    

DOI:10.1002/jemt.1060120204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractHIV particles were usually seen on the surface of established lymphoid cells derived from AIDS patients or on CEM cells infected with HIV, and sometimes in cytoplasmic vacuoles. The virus particles were formed by a budding process from the plasma membrane of an infected cell. The budding particles were of a doughnut form. Various profiles of virus particles were seen extracellularly: type 1 had a bar‐shaped, electron‐dense core, type 2 had a central and type 3 an eccentric electron‐dense round core, type 4 was doughnut‐shaped, and type 5 had a layered core. However, projection patterns of the AIDS virus model suggested that type 1, 2 and 3 particles are similar. Therefore, the AIDS virus may be one of three main types: with or without a dense core, and with a layered core. It is thought that a particle with a layered core and a doughnut‐type particle may be immatur

ISSN:0741-0581    

DOI:10.1002/jemt.1060120205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractRecent studies on lysosomal movements during heterophagy and autophagy performed in our laboratory for the past several years were reviewed; methods for the investigation of lysosomes and the cytoskeleton in these studies mainly involved electron microscopic cytochemistry.Lysosomal movements during heterophagy were observed in cultured rat alveolar macrophages taking up horseradish peroxidase (HRP) and rat peroxidase‐antiperoxidase (PAP) by fluid‐phase pinocytosis and adsorptive pinocytosis, respectively. A characteristic lysosomal change which was induced by the pinocytosis was the appearance of long, threadlike lysosomes (nematolysosomes) in the cytoplasm. The effects of actin filament destabilizer and antimicrotubular drug on lysosomal changes revealed that the appearance of nematolysosomes was dependent on the presence of both actin filaments and microtubules. The close morphological relationship between lysosomes and cytoskeletal elements, such as actin filaments and microtubules in the alveolar macrophages, supports the participation of the cytoskeletal system in the regulatory mechanism of lysosomal movements.In the study of the lysosomal wrapping mechanism (LWM), which is one type of lysosomal movement that occurs during autophagy, it was found that the occurrence of LWM was dependent on energy—namely, the supply of ATP—and on the presence of actin filaments. However, deconstruction of microtubules induced or favored the occurrence of LWM. It is conceivable that the LWM is also related to the cytoskeletal system.We conclude that intracellular dynamics of lysosomes during heterophagy and autophagy are largely a consequence of complicated modulation by the cytoskeletal

ISSN:0741-0581    

DOI:10.1002/jemt.1060120206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe three‐dimensional fine architecture of the red pulp of human and animal spleens, which as fixed by a modified version of the arterial and venous pressure‐loading perfusion fixation (AVPL perfusion fixation) method, is demonstrated by scanning and transmission electron microscopy. In the human spleen, changes in splenomegalias associated with hereditary spherocytosis and chronic portal hypertension are also introduced in addition to the normal architecture of the red pulp of spleens removed from patients with stomach cancer. The AVPL perfusion fixation of these spleens clearly visualized complicated three‐dimensional fine architecture of the red pulp and provided much important information on in situ morphology and dynamic change of the terminal vascular bed, including venous pressure‐dependent size change of the stomata and three‐dimensional shapes of the capillary terminal, with positive proof of their opening into the cordal reticular tissue. In studies of the spleen associated with portal hypertension, the AVPL perfusion fixation is considered a necessary technique for analysis of the structural deviation closely relating to a very high venous

ISSN:0741-0581    

DOI:10.1002/jemt.1060120207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractIn 1985 we developed an ultrahigh‐resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope.Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 X, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes.Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three‐unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments.We assume that ultrahigh‐resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomed

ISSN:0741-0581    

DOI:10.1002/jemt.1060120208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractUsing an ultrahigh‐resolution scanning electron microscope (SEM), an attempt was made to directly visualize antibody molecules at antigenic sites in rat pancreas or on silicone plates. Although individual antibody molecules could not be discerned, a fluffy meshwork, probably indicating several molecules, was seen. With further improvements in specimen preparation, the high‐resolution SEM promises to be an important tool in examining individual antibody‐antigen sites without the need of an electron‐dense label such as colloid

ISSN:0741-0581    

DOI:10.1002/jemt.1060120209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractCytoskeletons underneath the postsynaptic membrane of neuromuscular junctions were studied by using a quick‐freeze deep‐etched method and immunoelectron microscopy of ultrathin frozen sections. In a quick‐freeze deep‐etched replica of fresh, unfixed muscles, 8.9 ± 1.5‐nm particles were present on the true postsynaptic membrane surface. Underneath this receptor‐rich postsynaptic membrane, networks of fine filaments were observed. These cytoskeletal networks were more clearly observed in extracted samples. In these samples, diameters of the filaments which formed networks were measured. In the platinum replica, three kinds of filament were recognized—12 nm, 9 nm, and 7 nm in diameter. The 12‐nm filament seemed to correspond to the intermediate filament. The other two filaments formed meshworks between intermediate filaments and plasma membrane. In ultrathin frozen sections vinculin label was localized just beneath the plasma membrane. Thirty‐six percent of the label was within 18 nm from the cytoplasmic side of the plasma membrane and 50% was within 30 nm. Taking the size of the vinculin molecule into account, it was concluded that vinculin is localized just beneath the plasma membrane and might play some role in anchoring filaments which formed meshworks underneath t

ISSN:0741-0581    

DOI:10.1002/jemt.1060120210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0741-0581    

DOI:10.1002/jemt.1060120211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY