摘要:

AbstractRat soleus muscle Z‐lines and Z‐line anomalies induced by neostigmine methyl sulfate (NMS) and cat soleus muscle Z‐line and Z‐line anomalies induced by tentomy were examined by electron microscopy before and after dissection of muscle fibers with Ca2+‐activated neutral protease (CAF) to elucidate structural properties of Z‐lines and related Z‐line‐type structures. In both normal and treated muscles, interdigitation of thin (6–7 nm) filaments, which were continuous with I‐filaments (actin) from adjacent sarcomeres, was observed at the Z‐line in longitudinal section.Both neostigmine methyl sulfate and tenotomy treatments induced muscle atrophy associated with Z‐line degradation, streaming, and irregular distribution and accumulation of Z‐line material and Z‐rod formation. Tenotomized muscle also was characterized by the presence of N‐line‐like bands and I‐Z‐I brushes. CAF digestion removed the electron‐dense covering material from Z‐rods and revealed a backbone of actin filaments. The origin of Z‐rods, their structural similarity to Z‐lines in longitudinal and cross section, and their susceptibility to CAF indicate that Z‐rods are directly related to native Z‐lines and are probably lateral polymers of a basic Z‐line unit.The regular square net alignment (22 nm) of I‐filaments (actin) in cross sections of I‐Z‐I brushes which contain no N‐lines suggests that the I‐square net arrangement near the Z‐line is determined by Z‐filament‐actin filament interaction rather than by the N‐line or other factors.The results suggest that I‐filaments (actin) penetrate the mammalian Z‐line and are Z‐line constituents and that the width of Z‐lines and the length of Z‐rods are determined by the amount of overlap of actin filaments. The perpendicular periodicity of Z‐rods and the zigzag‐oblique arrowheadli

ISSN:0003-276X    

DOI:10.1002/ar.1092060402

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effects of chronic ethanol ingestion on an organelle known to be involved in protein synthesis were studied cytologically in nerve cells of the adult hamster. Twenty‐six animals were administered standard laboratory chow and either tap water (controls) or a 15% ethanol solution (experimentals) for a period of 7 weeks. Brains were perfusion‐fixed, sectioned transversely, and stained with buffered thionin for microscopic analysis. Reported here are changes in an RNA‐rich intranucleolar body (INB) seen in facial motor neurons and cerebellar Purkinje cells of the golden hamster. After chronic ethanol ingestion, the size and frequency of the INB increased significantly in both cell populations. Theoretical considerations are discussed concerning the correlation between this apparent storing of nucleolar RNA/RNP and the biochemical evidence of other investigators for ethanol‐induced alterations in RNA/protein synthesis and utilization in

ISSN:0003-276X    

DOI:10.1002/ar.1092060403

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

年代:1983

数据来源: WILEY

摘要:

AbstractMandibular condyles of fetal mice 19 to 20 days in utero were kept in an organ culture system for up to 10 days. After 2 days in culture the cartilage of the mandibular condyle appeared to have maintained all its inherent structural characteristics, including its various cell layers: chondroprogenent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic. After 5 days in culture no chondroblasts could be seen and, instead, the entire cartilage was occupied by hypertrophic chondrocytes. At the same time, the mesenchymal cells at the chondroprogenitor zone differentiated into osteoblasts which produced osteoid. Light microscopic examinations showed that the newly formed osteoid did not stain with acidic toluidine blue or with alcian blue, but stained intensively with the van Gieson stain and with Periodic acid‐Schiff (PAS). The osteoid reacted with antibodies against type I collagen but not with antibodies against type II collagen. Electron microscopic examinations showed that the mineralization appeared to be associated with collagen fibers in bone rather than with matrix vesicles in the cartilage. The process of bone formation progressed with time and by the 10th day new bone replaced almost the entire cartilage, thus forming an expanded layer of membrane bone. This in vitro system represents an experimental model whereby undifferentiated precursor cells transform into osteoblasts with the subsequent formation of a typical membrane bon

ISSN:0003-276X    

DOI:10.1002/ar.1092060404

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

年代:1983

数据来源: WILEY

摘要:

AbstractFollowing perfusion fixation of livers from fetal, neonatal, and adult sheep, the ultrastructure of the fenestrated sinusoidal endothelium was examined. In contrast to an earlier report which utilized immersion fixation, we found the fenestrae to be unoccluded by diaphragms or basal lamina, thus offering only a discontinuous barrier between the blood and the space of Disse and hepatocytes. This observation was confirmed by perfusing the liver with marker particles. The fenestrae appear, therefore, to have a sieving function, regulating the metabolism of particulate matter such as lipoproteins in sheep in a similar manner to that which has been shown to occur in rats.

ISSN:0003-276X    

DOI:10.1002/ar.1092060405

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe topographic distribution of blood vessels in Peyer's patches of mice was studied by light and scanning electron microscopy with whole mounts of flattened gut segments and vascular corrosion casts. Peyer's patches are imbedded in the intestinal wall and share its blood supply. Two to four mural trunks may contribute to the area of the patch. In and around the lymphoid nodules the microcirculation is highly specialized. The nodule is permeated by a meshwork of fine capillaries that is supplied by arterioles entering on the serosal and lateral surfaces. Blood flow to the lymphoid nodule appears tobe monitored by arterial sphincters; the dense lymphatic tissue can also beby passed by arteriovenous communications. An extensive venous network encircles the nodule. Most of these venules are lined by high endothelium which is penetrated by lymphocytes. The geometry of these vessels suggests a slow and turbulent flow in these vascular segments that may aid margination of lymphocytes. A planar capillary plexus lies subjacent to the mucosal epithelium in the dome area.

ISSN:0003-276X    

DOI:10.1002/ar.1092060406

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

年代:1983

数据来源: WILEY

摘要:

AbstractA technique was developed that allowed the in vivo observation of Peyer's patches in the mouse for several hours. Untreated animals and animals depleted of lymphocytes were used. In this species, blood vessels associated with the lymphoid nodules are readily visible through the thin serosal muscle coat. High‐endothelium venules are recognized by the large number of refractile cells that adhere to the luminal surface. A colloidal carbon suspension injected intravenously labeled high‐endothelium venules and was only rarely seen in arterial and capillary segments or in venules of the gut parenchyma. When fluorescein isothiocyanate‐labeled (FITC‐labeled) syngeneic spleen cells were injected, they appeared in vessels of the Peyer's patch within a few seconds and began to adhere to the luminal surface of high‐endothelium venules. In untreated animals, peak numbers of fluorescent cells were reached after about 20 min. Many adhered but some were swept away. In lymphocyte‐depleted animals, however, peak numbers were reached after only a few minutes and most cells remain

ISSN:0003-276X    

DOI:10.1002/ar.1092060407

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

年代:1983

数据来源: WILEY

摘要:

AbstractHigh‐endothelium venules of mouse Peyer's patches were examined by scanning electron microscopy, and a quantitative assessment was made of the location of lymphocytes in relation to endothelial cells. Untreated mice and mice with markedly depressed levels of circulating lymphocytes were used. Lymphocytes were divided into adhering and migrating cells and as to association either with the body of the endothelial cell or with its cell border. Over 90% of all adhering cells and the great majority of migrating lymphocytes were located at the cell border. The exception was one animal in which most migrating lymphocytes appeared to penetrate the endothelial cells. Our data lend strong support to the currently held view that most migrating lymphocytes traverse the endothelium by following an intercellular path but that, under certain conditions, lymphocytes may penetrate the cytoplasm of endothelial cell

ISSN:0003-276X    

DOI:10.1002/ar.1092060408

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe superficial zone of the femoral head articular cartilage of 5‐ to 15‐day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle ofthe zone appeared similar but with less cytoplasm. At the articular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: (1) Degenerating chondrocytes moved up through the superficial zone tothe articular surface and were shed into the joint space. This movement maybe facilitated by the network as part of neonatal cartilage development. (2) During joint formation, the surface of the articular cartilage was eroded down tothe chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar netw

ISSN:0003-276X    

DOI:10.1002/ar.1092060409

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe soleal line in 167 left and 163 right tibiae has been studied. The line often does not follow the textbook description. It commences well below the fibular facet and ends well down nearer the middle of the bone on the medial border. It generally shows mixed characters of a line, a wide line, a ridge, ora groove. The line is frequently absent in the upper third. In the middle third, it is seen as a wide line or as a ridge varying from 1 to 2 mm in height. In the lower third the line presents itself as a ridge. In the middle and lower thirds, the line is often seen as a depression varying from 1 to 2 mm in depth. The line shows a left‐sided dominanc

ISSN:0003-276X    

DOI:10.1002/ar.1092060410

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

年代:1983

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092060401

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

年代:1983

数据来源: WILEY