摘要:

AbstractBasement membranes (BMs) were first described in the mid‐19th century, but they were not isolated and prepared for compositional studies until nearly 100 years later. Early methods of isolation were carried out on renal glomeruli, which were first sub‐fractionated from kidney tissues by sieving. BMs were then isolated from the glomeruli by ultrasonic disruption, which, following low speed centrifugation, yielded “purified” but highly fragmented BM material. In an effort to obviate the mechanical damage to BMs produced by ultrasound, a sequential detergent solubilization technique was introduced that resulted in morphologically intact BMs from a variety of tissue sub‐fractions. This was highly advantageous because “acellular” BMs produced by the procedure could be examined critically by light and electron microscopic methods. Subsequently, this procedure has been utilized to demonstrate the substructural heterogeneity of vascular and non‐vascular BMs from a wide variety of animal species. The current review describes the results of scanning and transmission electron microscopic studies of acellular BMs prepared from renal glomeruli and from the retinal microvessels of the eye. These BMs are of particular interest to basic scientists and clinicians because they are altered in several disease states, most notably diabetes mellitus. An effort is made to point out the implications of glomerular and retinal vessel BM changes to the pathogenesis of diabetic kidney and retinal vessel BM disease. © 1994

ISSN:1059-910X    

DOI:10.1002/jemt.1070280302

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

年代:1994

数据来源: WILEY

摘要:

AbstractSystemic lupus erythematosus is a disease that is particularly suited for studies of glomerular basement membrane pathology. Classification of the renal pathology of lupus nephritis is usually based on light microscopic features, combined with immunofluorescence findings and electron microscopic alterations. Study of renal biopsy helps to distinguish potentially reversible and irreversible disease, and to estimate prognosis of patients with lupus nephritis. Moreover, studies of human disease, as well as the availability of animal models and in vitro cell culture systems employing biochemical and molecular biological studies of extracellular matrix, have led to a considerable increase in knowledge of the pathogenetic events underlying derangements of the glomerular basement membrane in lupus nephritis. © 1994 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070280303

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlthough remarkable progress has been made during the last two decades concerning the biosynthesis, expression and assembly of extracellular matrix (ECM) macromolecules in nonneural cells, we are still far from a complete understanding of the role and function of the ECM and the basement membrane (BM) in the central nervous system (CNS). With the aid of correlative light and electron microscopic, Golgi and immunohistochemical studies of the developing neural tube of both early human fetus and mouse, we have shown that the establishment of the pial‐glial barrier (PGB) is one of the earliest histogenetic events in neurogenesis. This is accomplished by coordinated interaction among the processes of radial glia, various ECM components, and mesenchymal cells at the pial surface, with the formation of a BM that tightly abuts the glia limitans. The PGB and the BM appear to be critical to the migration and final positioning of neurons and to the differentiation of the laminar cortical pattern within the developing neopallium. This hypothesis is further supported by our study of the brain of a human newborn infant in whom multiple sites of disruption of the BM and PGB resulted in abnormal neuronal migration and massive ectopia of neurons within the subarachnoid space, with abnormal cortical lamination. Finally, studies of the experimental cryogenic injury to the neonatal rat cerebrum have shown that the final positioning of neurons within the developing cortical plate appears to depend largely on the reconstitution of the BM and PGB, which presumably provide crucial positional signals for migrating neurons. Also, one of the essential reparative features seen following cryogenic injury to the adult rat cerebrum is an orderly and dynamic interaction between various ECM components and neural cells, resulting in the formation of the BM. © 1994 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070280304

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlzheimer's disease (AD) is one of several systemic and cerebral diseases that involve the abnormal deposition of fibrillar proteins called amyloids. All amyloids share conformational and staining characteristics, as well as an association with resident tissue macrophages and two extracellular matrix components [heparan sulfate proteoglycan (HSPG) and amyloid P component]. Vascular, glomerular, and Schwann cell basement membrane pathologies have been documented in many forms of amyloidosis, and often amyloid fibrils fuse to and project from the basement membrane in these diseases. The present report demonstrates the vascular basement membrane (VBM) alterations in AD autopsy samples, and details the methodologies used.Electron microscopy reveals the fusion of amyloid fibrils with the VBM and the alteration of the VBM in the absence of amyloid accumulation. Double‐labelling and pre‐embed immuno‐electron microscopy techniques demonstrate the colocalization of amyloid P component and VBM components with amyloid, and also reveal that amyloid P component is not localized to the cerebral VBM. Finally, a novel correlative light/electron microscopy technique demonstrates the association between amyloid P component and cerebral resident tissue macrophages, the microglia. Taken together, these data suggest that the physicochemical processes of amyloid formation, rather than amyloid deposition, may be responsible for VBM pathology. © 1994 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070280305

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper, the use of immunohistochemistry for the analysis of basement membrane components and related extracellular matrix proteins in human cancer is reviewed. Basement membranes in cancer are dynamic structures that are constantly degraded but also deposited, in close collaboration between tumor cells and stromal cells. Basement membrane immunohistochemistry, using antibodies against type IV collagen and laminin, appears to be a useful tool in the analysis of lesions on the borderline between premalignant and malignant. Basement membrane interruptions, however, cannot be used as the only criterion for the diagnosis of malignancy. Type VII collagen is often degraded prior to type IV collagen and laminin in early invasion. This protein also tends to be expressed in carcinomas when it is not found in the corresponding normal tissue. Tenascin seems to play a complex role in the development of human tumors, including promotion of cell growth and differentiation, cell migration during invasion, and tissue remodeling during the development of primary and metastatic lesions. Further systemic exploration of extracellular matrix molecules in neoplasms should yield new information relevant for cancer biologists and useful in cancer diagnosis. © 1994 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070280306

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe studied the effect of high thoracic aorta cross‐clamping, complete transverse section of the spinal cord at Th6level, and combined hemisection at Th6level followed later by high thoracic aorta cross‐clamping upon the morphology and number of identified presynaptic knobs in lumbosacral segments in dogs. In animals surviving 48‐72 hours after high thoracic aorta cross‐clamping the occurrence of an unusual form of boutons accompanied by periboutonal halo in L3‐S1segments was found. According to the bouton size and light as well as electron microscopic appearance, four types, i.e., light giant (T1), dark enlarged (T2), light giant with periboutonal halo (T3), and giant disintegrating (T4) boutons were detected after 48 and 72 hour reperfusion. The appearance of four boutonal types in the lumbosacral segments is caused by spinal cord ischemia secondary to high thoracic aorta cross‐clamping followed by 48 or 72 hour reperfusion. At the end of the sixth reperfusion day no signs of enlarged and giant boutons were detected in L3‐S1segments. A statistically significant increase of enlarged and giant boutons was noted at the end of the third reperfusion day in comparison with 48 hour survival. After spinal cord transection at midthoracic (Th6) level, followed by 72 hour survival, no such unusual synaptic knobs could be found in L3‐S1segments. The laminar distribution pattern of T1‐T4types based on light microscopic analysis and confirmed electron microscopically is characteristic and strictly bound to those spinal cord gray matter layers which serve as main termination sites of the descending cortical, brain stem, as well as long propriospinal projections in the lumbosacral segments (laminae V‐VIII). A statistically significant increase of enlarged and giant boutons was found in the intermediate zone (lamina VII). Hemisection at midthoracic level (Th6) followed later by 30 minute high thoracic aorta cross‐clamping and 48 hour reperfusion caused a marked decrease of enlarged and giant boutons in L3‐S1segments on the hemisectioned side in comparison with the contralateral one. Large amounts of irregularly arranged round vesicles and tubular profiles were disclosed in the boutonal matrix of T1, T3, and T4types in L3‐S1segments of animals subjected to 30 minute high thoracic aorta cross‐clamping followed by 72 hour reperfusion. Accumulation of tubular and membranous materials was invariably seen in the bulbous enlargement of the terminal axonal branch. Therefore, it is reasoned that the ischemia‐induced delayed‐onset paraplegia is closely related to synaptic uncoupling, resulting after ischemia‐reperfusion damage of the spinal cord interneurons acting as postsynaptic neurons for long descending spinal cord afferents of cortical and brain st

ISSN:1059-910X    

DOI:10.1002/jemt.1070280307

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

年代:1994

数据来源: WILEY

摘要:

AbstractVarious salivary glands in senescent humans and other animals have been examined extensively to characterize the structural and functional changes that occur during aging. Although a wide range of different structural changes, involving both the parenchymal and stromal tissues, have been described, it is unclear how any of these changes affects the function of the salivary glands. One major change in structure is the reduction in the volume of acini with a concomitant increase in the ductal volume. Despite this loss of functional acini, the salivary output and the contents seem to be unaltered, or minimally altered, due to aging. One consistent change observed in many salivary glands of aged animals is the decline in the rate of synthesis of proteins and their messenger RNA (mRNA). However, the salivary acinar cells from aged animals can synthesize secretory proteins at an elevated rate just as effectively as those from their younger counterparts in response to external stimuli, which are known to enhance the rate of protein synthesis. Thus, it appears that the salivary acinar cells, which remain structurally intact during aging, seem to retain their functional efficiency. Furthermore, these acinar cells, although reduced in number, are sufficient in quantity to carry out most of the salivary gland functions. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of Ameri

ISSN:1059-910X    

DOI:10.1002/jemt.1070280308

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

年代:1994

数据来源: WILEY

摘要:

AbstractA comparative study of some aspects of freeze‐substitution as a preparative method for X‐ray microanalysis of diffusible ions in biological specimens was carried out. Four substitution fluids were compared with each other and with cryosections. As criteria, elemental ratios as determined by X‐ray microanalysis of thin sections of mouse pancreas were used. Freeze‐substitution for 3 weeks in diethy ether or for 2 days in tetrahydrofurane gave results comparable to those obtained in cryosections. Slow warming to room temperature after freeze‐substitution in tetrahydrofurane gave slightly better results than fast warming. Freeze‐substitution in acetone resulted in noticeable loss and redistribution of ions and freeze‐substitution in methanol gave very poor results. © 1994 W

ISSN:1059-910X    

DOI:10.1002/jemt.1070280309

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

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070280310

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

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070280301

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

年代:1994

数据来源: WILEY