Showing papers on "Ultrastructure published in 1975"
TL;DR: In the vast majority of fibers the colony arises from only one highly localized site along the fiber suggesting that proliferative competence is restricted to extremely few fiber nuclei, as well as by the observation that fiber degeneration occurs rapidly and is completed within 24 hr after explantation.
172 citations
TL;DR: The formation of the myelin sheath both during original myelinogenesis and during remyelination after segmental demyelinations may be different from the generally accepted normal regular helical construction.
171 citations
Book•
08 Apr 1975
TL;DR: The mechanoreceptors of the mammalian skin ultrastructure and morphological classification ultrastru PDF is available at the online library.
Abstract: THE MECHANORECEPTORS OF THE MAMMALIAN SKIN ULTRASTRUCTURE AND MORPHOLOGICAL CLASSIFICATION ULTRASTRU PDF Are you looking for the mechanoreceptors of the mammalian skin ultrastructure and morphological classification ultrastru Books? Now, you will be happy that at this time the mechanoreceptors of the mammalian skin ultrastructure and morphological classification ultrastru PDF is available at our online library. With our complete resources, you could find the mechanoreceptors of the mammalian skin ultrastructure and morphological classification ultrastru PDF or just found any kind of Books for your readings everyday.
143 citations
TL;DR: Electron photomicrographs of material decalcified by this procedure are superior to those from EDTA-treated tissue and show few of the deleteriour effects produced by EDTA.
Abstract: Decalcification of echinodcrm tissues for electron microscopy can be achieved after glutaraldehyde-osmium firation by treatment with a 1:1 mixture of 2% ascorbic acid and 0.3 M NaCI for 12-24 hours. Electron photomicrographs of material decalcified by this procedure are superior to those from EDTA-treated tiasue and show few of the deleteriour effects produced by EDTA.
135 citations
Journal Article•
TL;DR: The ultrastructure of the three specialized bone cells are described in relation to their function and characteristics are multiple nuclei, and abundance of mitochondria, a sparcity of RER and clusters of ribosomes.
Abstract: The ultrastructure of the three specialized bone cells are described in relation to their function. Osteoblasts are the bone forming cells with an abundance of RER and a large Golgi area. Osteoblasts and osteocytes form an integrated cell system connected with each other by cell processes filled with actin-like filaments and joined by specialized cell junctions, probably gap junctions. Osteoclasts resorb bone. Characteristics are multiple nuclei, and abundance of mitochondria, a sparcity of RER and clusters of ribosomes. Lysosomes and vesicles contain hydrolytic enzymes. The resorbing area consists of a ruffled border completely encircled by a clear zone.
123 citations
TL;DR: The ultrastructure of logarithmic‐growing cells and of resting cells in laboratory cultures of Amphora coffaeformis (Ag.) Kütz and the fine structure of cells during growth resumption when exposed to light at 25 c is presented.
Abstract: SUMMARY
The ultrastructure of logarithmic-growing cells and of resting cells in laboratory cultures of Amphora coffaeformis (Ag.) Kutz. isolated from deep ocean water was examined using electron and light microscopy. The acid Phosphatase activity, chlorophyll a and lipid content were assessed at weekly intervals of resting cell formation during cold-dark treatment, simulating deep ocean water. Approximately 4 wk are required to complete resting cell formation. During the first week, the cytoplasm undergoes extensive transformation and lysosomal activity is observed. Large vacules decrease in size and many small ones develop, the mitochondria become fewer and one or more massive mitochondria appear possibly by fusion of smaller ones; the cytoplasm becomes densely granular. During the second and third week, the cytoplasm continues to contract, lipid bodies begin to develop and the plastid becomes densely stained. At the fourth week, the mature resting cell is formed containing one or more massive mitochondria, a well-formed plastid, and granular cytoplasm containing occasional lipid droplets. There is no change in frustule morphology and the cytoplasm does not produce a protective layer. The variation in chemical constituents correlates with microscopic structure of the cells. The fine structure of cells during growth resumption when exposed to light at 25 c is presented. Previous reports of viable, chlorophyll-containing cells at great depths in the ocean may be explained by the results reported in this paper.
91 citations
TL;DR: Elastin was diminished and microfilaments were visible throughout the entire fiber of acquired and congenital cutis laxa, and electron-dense, amorphous or granular layers that alternate with relatively electron-light layers were deficient.
Abstract: Specimens from one case each of acquired and congenital cutis laxa were examined by electron microscopy. Elastic fibers of the dermis and subcutaneous arteries and veins were found to have similar changes. Elastin was diminished and microfilaments were visible throughout the entire fiber. Electron-dense, amorphous or granular layers that alternate with relatively electron-light layers were deficient. This electron-dense substance was unevenly aggregated within or in the vicinity of elastic fibers. In the congenital case, the aggregation and deposition of the electron-dense substance was often pronounced. In the vein, deficient deposition of elastin and admixture of microfilaments and amorphous substance were also found. Such admixture was often encircled by fibroblasts or smooth muscle cells. In the artery, multiplication of basal lamina was seen. Collagen fibers and anchoring fibrils of the skin were normal.
86 citations
TL;DR: Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis.
Abstract: The association of rumen bacteria with specific leaf tissues of the forage grass Kentucky-31 tall fescue (Festuca arundinacea Schreb.) during in vitro degradation was investigated by transmission and scanning electron microscopy. Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis. Rumen bacteria appeared to degrade the mesophyll, in some cases, and phloem without prior attachment to the plant cell walls. The degradation of bundle sheath and epidermal cell walls appeared to be preceded by attachment of bacteria to the plant cell wall. Ultrastructural features apparently involved in the adhesion of large cocci to plant cells were observed by transmission and scanning electron microscopy. The physical association between plant and rumen bacterial cells during degradation apparently varies with tissue types. Bacterial attachment, by extracellular features in some microorganisms, is required prior to degradation of the more resistant tissues.
TL;DR: The impression in these eight cases studied is consistent with the view that bronchiolo‐alveolar carcinomas are indistinguishable at the ultrastructural level from other bronchogenic adenocarcinomas.
Abstract: Ultrastructural features were correlated with a series of special staining reactions in eight cases of bronchiolo-alveolar carcinoma. Ultrastructural, all tumors were similarly composed of large cells with abundant cytoplasm and small nuclei in close contact with each other. Straight membranes or complex interdigitations occurred within adjacent tumor cells, attached to each other by scattered desmosomes. Microvilli or cilia abutted from free surfaces of the cells, and were noted in different stages of evolution. Numerous organelles were seen in the cytoplasm, including prominent mitochondria and single or coalescent secretory vacuoles with granular matrix resembling mucin. Other cytosomes less commonly found were irregular, partially lamellated inclusions and dark, homogeneous structures without limiting membranes. The stroma of the tumors was rich in elastin and collagen. Both the number of secretory vacuoles in the cytoplasm of tumor cells and the amount of connective tissue fibrils in the stroma of the tumors correlated well with the findings in the series of special staining reactions. No definite ultrastructural feature was present to identify the tumors as orginating from Type II alveolar epithelial cells, but the possibility exists that they arose in the bronchiole, from undifferentiated basal cells or mucinous cells per se. Our impression in these eight cases studied is consistent with the view that bronchiolo-alveolar carcinomas are indistinguishable at the ultrastructural level from other bronchogenic adenocarcinomas.
TL;DR: The seminiferous tubules of the dog testis are surrounded by a boundary tissue composed of a basal lamina and a layer of peritubular cells that is from one to six cells thick.
Abstract: The seminiferous tubules of the dog testis are surrounded by a boundary tissue composed of a basal lamina and a layer of peritubular cells that is from one to six cells thick. Myoid cells, arranged in a layer only one cell thick. are the innermost cells of the boundary tissue. These cells are characterized by the presence of numerous microfilaments 5 nm in diameter. micropinocytotic vesicles, intracellular densities near the plasma membrane, and a basal lamina on both faces. In the interstitial tissue, clusters of Leydig cells are enveloped by a basal lamina. and the individual cells are separated by a varying intercellular space. Leydig cells are joined by gap junctions, septate-like junctions, and rudimentary desmosomes. Within their cytoplasm are many 5-nm wide microfilaments. The smooth endoplasmic reticulum is seen either as tubules or simple cisternae separated by microfilaments in the less developed Leydig cells and as extensive whorls of fenestrated smooth endoplasmic reticulum surrounding lipid droplets or mitochondria in the larger Leydig cells. Another cell type is present in the dog testis that has many of the cytological characteristics of the Leydig cell. This cell, however, is located within the boundary tissue of the seminiferous tubules between the myoid cell layer and the lymphatic endothelium. These Leydig-like cells may represent a stage in Leydig cell differentiation. The testicular lymphatics occur both as vessels and as sinusoids and often separate the boundary tissue from the interstitial tissue.
TL;DR: 2,4-D did not inhibit the induction of embryoids, although it prevented their further development into plantlets, and electron microscopy of the tissue in active proliferation showed highly cytoplasmic cells rich in organelles and profiles of the endoplasmic reticulum.
TL;DR: It was observed at the electron microscope that the architecturally complex terminal tubules, proacinar, acinar and striated duct cells retained mitosis the major ultrastructural features they exhibited in interphase.
Abstract: The development of the submandibular gland of the rat was studied between days 2 and 55 of the postpartum. Besides confirming previous ultrastructural findings wer observed at the electron microscope that the architecturally complex terminal tubules, proacinar, acinar and striated duct cells retained mitosis the major ultrastructural features they exhibited in interphase. The ultrastructure of cells that were in the S period of the proliferative cycle was evaluated in high resolution autoradiographs from rats injected with thymidine-H3. All cell types were thus studied and no obvious cytoarchitectural modifications could be detected in these cells preparing for dividion. We obtained ultrastructural evidence that between days 20 and 30 some terminal tubule cells undergo transformation into acinar cells. The intercalated duct cells showed the highest rate of proliferation and the lowest daily increment in number. This suggests that cells from the intercalated ducts migrate to the neighboring morphological compartments. Quantitative data on the rate of cell proliferation and accumulation in the straited duct indicated that cells from the intercalcated ducts should differentiate into straited duct cells. Differentiation of intercalated duct cells into the terminal tubule cells was observed with the electron microscope.
TL;DR: Dendritic changes paralleled those of perikarya save that proliferation of subsurface cisterns and autophagic bodies was absent and may have originated from retrograde degeneration of cortical neurons induced by lateral funiculotomy.
Abstract: Described here are ultrastructural changes in neurons of feline red nucleus exhibiting axon reaction after unilateral rubropsinal tratotomy at the C-2 level and surviving 2 to 65 days. Ultrastructural alterations included neurofilamentous hyperplasia; proliferation of smooth ER; temporary disappearance of organized granular ER with partial substitution by haphazardly arranged, broad cisternal profiles; loss of rosette ribosomes and occurrence of single ribonucleoprotein granules or an intercisternal amorphous density; increased numbers of subsurface cisterns and allied structures, often disposed in stacks; vesiculation and vacuolation of Golgi cisternae; prevalence of autophagic bodies derived in part from Golgi complexes; probable mitochondrial hyperplasia and various qualitative changes in these organelles; an increase in lipofuscin. Dendritic changes paralleled those of perikarya save that proliferation of subsurface cisterns and autophagic bodies was absent. Abnormalities of myelinated axons and boutons occurred and may have originated from retrograde degeneration of cortical neurons induced by lateral funiculotomy. Some perikarya were devoid of axosomatic boutons. Ultrastructural changes varied with the length of postoperative survival and were, at least partly, reversible. Chromatolysis was detectable light microscopically before ultrastructural abnormality appeared. The bearing of transneuronal mechanisms on axon reaction of central neurons and the protective effect of section of axons beyond the site of origin of collaterals are discussed.
TL;DR: Evidence is presented showing that the subcuticular region of the lateral chords of the adult subperiodic Brugia malayi comprises a functional complex of basal infoldings, multivesicular bodies, and associated mitochondria, which is probably engaged in the exchange of solutes across a permeable cuticle.
Abstract: The ultrastruct of the adult subperiodic Brugia malayi (Brug, 1927) within pulmonary arteries of male jirds (Meriones unguiculatus) was studied by transmission electron microscopy. The cuticle consists of 10 sublayers (2 of which are prominently banded) and a typical outer unit membrane. Evidence is presented showing that the subcuticular region of the lateral chords comprises a functional complex of basal infoldings, multivesicular bodies, and associated mitochondria, which is probably engaged in the exchange of solutes across a permeable cuticle. Microbodies with paired, prominent cores, intracisternal A-particle viruslike bodies, nonstaining glycogen patches, and other structures are also present in the lateral chords. The platymyarian somatic musculature shares some coelomyarian characteristics, e.g., apparent neuromuscular connections and prominent glycogen deposits surrounded by mitochondria and other organelles. The alimentary tract has features typical of many nematodes. The luminal segments of the male and female reproductive tracts and their germinal products, excluding microfilariae, are described. Affinities with related species are discussed.
TL;DR: The hypothesis that the mechanism of C-banding involves the selective loss of non C- band chromatin is supported, as the evidence indicates that these interchromosomal fibres are artefacts produced by the overlapping of dispersed chromatin fibres.
TL;DR: Changes in mesophyll ultrastructure with development and season are described for Abies balsamea, showing most cells appear to be fully mature and actively photosynthesizing at the time of budbreak.
Abstract: Changes in mesophyll ultrastructure with development and season are described for Abies balsamea. Cells mature sequentially during expansion of the needles. Most cells appear to be fully mature and actively photosynthesizing at the time of budbreak. Tannins appear early and accumulate throughout the growing season. Winter dormancy is marked by an accumulation of lipids throughout the cell, an aggregation of organelles around the nucleus, some loss of chloroplast structure, and a failure of chloroplasts to form starch grains. Reorganization of cell structure and resumption of synthetic activity in the spring occurs about 2 months before budbreak.
TL;DR: In this paper, the surface ultrastructure of Kupffer cells in the rat liver has been studied by scanning electron microscopy (SEM) and the results demonstrate that KUPffer cells are both significantly different and clearly distinct from endothelial cells.
Abstract: The surface ultrastructure of Kupffer cells in the rat liver has been studied by scanning electron microscopy (SEM). The results demonstrate that Kupffer cells are both significantly different and clearly distinct from endothelial cells. Kupffer cells have neither pores (and/or “sieve plates”) nor fenestrations, all of which are present in endothelial cells. They possess a stellate shape, and only indirectly, with slender and irregular evaginations, contribute to the lining of the sinusoidal wall. Furthermore, the luminal surface in some areas contains a large population of short microvilli, microplicae and invaginations. These elements form a kind of microlabyrinth which may correspond to the “worm-like” structures described by transmission electron microscopy (TEM).
TL;DR: The stroma and epithelium of human corneas that had been stored in organ culture medium for 10 to 22 days at 37 C were examined by light and electron microscopy and appeared to be viable.
Abstract: The stroma and epithelium of human corneas that had been stored in organ culture medium for 10 to 22 days at 37 C were examined by light and electron microscopy. Total corneal thickness was found to be doubled at ten days and there was no further increase even at 22 days. The posterior portion of the stroma was more hydrated than the anterior region. Stromal cells were reduced in number and normal-appearing cells were present only in superficial stroma. The epithelial basement membrane was irregular and thickened. Although the epithelium was reduced to three or four cells in thickness and the intercellular spaces were dilated, the epithelial cells contained normal subcellular organelles and appeared to be viable.
TL;DR: Frozen thin-sections of fresh medullary bone, which had been calcifying for 2 to 4 days, were prepared and examined in the electron microscope, and micrographs obtained may be a more accurate representation of cell ultrastructure.
Abstract: Frozen thin-sections of fresh medullary bone, which had been calcifying for 2 to 4 days, were prepared and examined in the electron microscope. The bone was obtained from male Japanese quail treated with estradiol valerate. Large numbers of 200–800 A electron dense granules, which consisted of 50–75 A subparticles, were seen within mitochondria. A population of electron-dense particles slightly smaller than ribosomes was also observed. Most granules were not present after conventional fixation, dehydration, embedding, sectioning and staining. Other structures which were visible, also on the basis of their intrinsic electron density, were nuclei with regions which resembled condensed chromatin, ribosomes and rough endoplasmic reticulum. By the use of osmium tetroxide vapor staining, inner and outer membranes and cristae of mitochondria were delineated. Other membranous components were not detected. Since very little loss or dislocation of cell components can occur during the preparation of frozen thin-sections, the micrographs obtained may be a more accurate representation of cell ultrastructure.
01 Jan 1975
TL;DR: Quantitative studies showed a 60% increase in the mean size and an increased proportion of larger mitochondria in intact 30 month-old perfused livers and the levels of cytochrome oxidase and malate dehydrogenase were slightly decreased with age but their cytochemical localization was unchanged.
Abstract: The ultrastructure of perfused livers and of mitochondrial fractions from 6 months and 30 month-old C57/BL mice were studied. In old mice the liver cell mitochondria were enlarged and rounded with a light “foamy”, vacuolated matrix, short cristae and a loss of dense granules. Quantitative studies showed a 60% increase in the mean size and an increased proportion of larger mitochondria in intact 30 month-old perfused livers. Endothelial and Kupffer cell mitochondria were smaller than those of the parenchymal cells.
Journal Article•
TL;DR: The articular cartilage in pyogenic arthritis, induced in rabbit by intra-articular injection of Staphylococcus aureus, was studied with the electron microscope and showed erosion of the surface and degeneration and necrosis of the chondrocytes starting from 24 hours onward, following the intra-artsic injection of bacteria.
Abstract: The articular cartilage in pyogenic arthritis, induced in rabbit by intra-articular injection of Staphylococcus aureus, was studied with the electron microscope. The cartilage showed erosion of the surface and degeneration and necrosis of the chondrocytes starting from 24 hours onward, following the intra-articular injection of bacteria. The surface erosion and chrondrocyte necrosis progressed rapidly. The changes are believed to be due mainly to liberation of lysosomal enzymes from the synovial cells and polymorphonuclear leukocytes.
TL;DR: In the fish kept under continuous light or in darkness, the pineal end-vesicle displayed a dilated lumen, and the outer segments of the receptors showed signs of degeneration, and alterations of cell organelles were observed in the photoreceptor and supporting cells.
Abstract: Ultrastructural changes of the pineal organ were investigated in the blind cave fish, Astyanax mexicanus, kept under continuous artificial light (5000 lux), in continuous darkness, and under natural light conditions. The pineal end-vesicle of the fish kept under natural photoperiod consisted of photoreceptor cells and supporting cells mixed with a few ganglion cells. The photoreceptor cells possessed well-developed outer segments with regularly arranged lamellar membranes. The supporting cells contained a number of lipid droplets and large globular cisternae filled with fine granules. In the fish kept under continuous light or in darkness, the pineal end-vesicle displayed a dilated lumen, and the outer segments of the receptors showed signs of degeneration. Furthermore, alterations of cell organelles were observed in the photoreceptor and supporting cells.
Journal Article•
TL;DR: Although the authors could not identify banded collagen fibrils in 10- to 14-day-old cultures by electron microscopy, the cells synthesized and secreted a collagen characterized as type I collagen, suggesting that the smooth muscle cells were actively engaged in protein synthesis.
TL;DR: A modification of the chromaffin reaction was employed in the ultrastructural localization of biogenic amines in the rat superior cervical ganglion, which revealed the presence of three cell organelles containing highly electron-dense material, namely large dense cored vesicles, small dense cORED vesicle, and a tubular reticulum.
TL;DR: It is suggested that the MP-to-YP transition of S. schenckii may be regulated by at least two mechanisms involving alterations of the biochemical and/or biophysical nature of the cell wall of the MP cell in response to the conversional stimuli.
Abstract: Fine details of the internal and external morphology of the in vitro mycelial phase (MP) to yeastlike phase (YP) transition of the dimorphic fungal pathogen Sporothrix schenckii are shown in electron micrographs of ultrathin sections. Morphological transformation at the ultrastructural level was observed to occur by direct formation of budlike structures at the tips and along the hyphae and by oidial cell formation. Direct budding of yeast from conidiospores was not observed. Early transitional forms arising by direct blastic action from the MP possessed conspicuous electron-dense microfibrillar material at the outer limits of the cell wall. The electron density of this microfibrillar material was enhanced by staining with acidified dialyzed iron. It is believed that this extracellular material may be composed in part of an acid mucosubstance. No acid phosphatase activity was associated with this microfibrillar material. This substance was found to be a characteristic of the outer limits of the cell wall of the YP of S. schenckii. Oidial YP cell formation occurred later during the transition. The cell wall of the developing oidial YP transitional form arose from an inner layer of the converting hyphae. No consupicuous alterations of the cytoplasmic content of the parent MP cell was observed during MP-to-YP transition. It is suggested that the MP-to-YP transition of S. schenckii may be regulated by at least two mechanisms involving alterations of the biochemical and/or biophysical nature of the cell wall of the MP cell in response to the conversional stimuli.
TL;DR: Understanding the in situ ultrastructure of normal human fibroblasts during growth in culture will permit systematic examination of such cells in a variety of pathological states.