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Showing papers on "Ultrastructure published in 1986"


Journal ArticleDOI
TL;DR: The association between Campylobacter-like organisms (CLOs) and lesions of the gastric mucosa was studied in 59 consecutive biopsies using Hematoxylin and eosin and Warthin-Starry silver stains and high-resolution light microscopy.
Abstract: The association between Campylobacter-like organisms (CLOs) and lesions of the gastric mucosa was studied in 59 consecutive biopsies. Hematoxylin and eosin and Warthin-Starry silver stains, as well as high-resolution light microscopy (HRLM) and transmission electron microscopy (TEM), were used. The organisms were found in intimate contact with foveolar cells showing abundant phagolysosomes and alterations of the intercellular complexes. CLOs also were seen in close proximity of parietal cells in resting phase, some of which showed degenerative changes. The findings are discussed in light of recent reports linking CLOs to the cause of gastritis.

176 citations



Journal ArticleDOI
TL;DR: It is concluded that in light microscopy the finding of Rocha- Lima's inclusions is the only definite morphologic evidence of the presence of bartonella in verruga lesions.
Abstract: Twenty-six verruga peruana nodules were studied. The presence of Factor VIII-related antigen and Ulex europaeus lectin binding, and the ultrastructural finding of rudimentary cell junctions and pinocytotic vesicles establish the endothelial character of the proliferating cells in the verruga nodules. Whereas superficial lesions could show an angiomatoid pattern, deep-situated nodules tended to present a compact type of growth. Electron-microscopic studies have shown that Bartonella bacilliformis was found abundantly in the extracellular spaces in the florid lesions and that no organisms were present in the late, resolving subcutaneous nodules. Although no true intracellular "viable" microorganisms were noted, pseudopods of cytoplasm entrapping one or two bacteria and surrounding matrix substance were seen often. The characteristics of cytoplasmic inclusions previously described in verruga cells as "chlamydozoa" were detailed. The ultrastructure of the inclusions corresponded to endothelial phagocytic cells in which complex invaginations of the cell surface had produced a labyrinth of interconnected channels and vacuoles containing degraded bacteria, extracellular matrix components, or both. We conclude that in light microscopy the finding of Rocha-Lima's inclusions is the only definite morphologic evidence of the presence of bartonella in verruga lesions.

107 citations



BookDOI
01 Jan 1986
TL;DR: When there are many people who don't need to expect something more than the benefits to take, this ultrastructure techniques for microorganisms book will probably make you feel curious.
Abstract: When there are many people who don't need to expect something more than the benefits to take, we will suggest you to have willing to reach all benefits. Be sure and surely do to take this ultrastructure techniques for microorganisms that gives the best reasons to read. When you really need to get the reason why, this ultrastructure techniques for microorganisms book will probably make you feel curious.

80 citations


Journal ArticleDOI
TL;DR: The visual evidence suggests that cell collapse was the result of autolysis in rice, and the pattern of cortical degeneration in rice was dissimilar to that reported elsewhere for Zea roots grown in an oxygen depleted environment.
Abstract: Webb, J. and Jackson, M. B. 1986. A transmission and cryo-scanning electron microscopy study of the formation of aerenchyma (cortical gas-filled space) in adventitious roots of rice (Oryza sativa).— J. exp. Bot. 37: 832-841. The initiation and development of aerenchyma in adventitious roots of rice (Oryza sativa) was studied in tissue up to approximately 36-h-old using transmission electron microscopy (TEM) and cryo scanning electron microscopy (cryo-SEM). Aerenchyma resulting from selective cortical cell collapse is a naturally occurring feature of rice roots. Evidence of some cortical cell disruption was noticeable by TEM in cells that were approximately 6-h-old; it became more advanced as the cells aged. At 12 h, early stages of cell wall breakdown and loss of cell turgidity were seen. Complete collapse of columns of cells had occurred by 24 h. In tissue that was 36-h-old, the senescent cytoplasm of many remaining cells began to disperse. The visual evidence suggests that cell collapse was the result of autolysis. This pattern of cortical degeneration in rice was dissimilar to that reported elsewhere for Zea roots grown in an oxygen depleted environment. Cryo-SEM revealed the occurrence of small structures within the cortex with the external appearance of miniature, intact cells which are not preserved during conventional SEM preparative procedures.

74 citations


01 Jan 1986
TL;DR: In this article, the infrastructure des microfibrilles du tissu conjonctif is examined chez la souris dans deux sites: la zonule ciliaire de l'œil and le coussinet plantaire.
Abstract: L'ultrastructure des microfibrilles du tissu conjonctif est examinee chez la souris dans deux sites: la zonule ciliaire de l'œil et le coussinet plantaire

65 citations


Journal ArticleDOI
TL;DR: Nine stages of choriogenesis have been discerned, replacing the four stages used so far, and the size of oocyte as compared with the whole follicle and the length of the chorionic appendages are identified.
Abstract: The characteristics of the stages of choriogenesis have been identified using light and electron microscopy. Nine stages have been discerned (11A, 11B, 12A, 12B, 12C, 13A, 13B, 14A, 14B), replacing...

64 citations



Journal ArticleDOI
TL;DR: Findings confirm that this pancreatic-type tissue induced in the livers of rats treated with polychlorinated biphenyls is morphologically and functionally identical to pancreatic acinar tissue.
Abstract: Pancreatic-type tissue induced in the livers of rats treated with polychlorinated biphenyls was characterized by transmission electron microscopy and high-resolution immunocytochemistry. The cells of pancreatic-type tissue were arranged as acini and in small groups. By electron microscopy the pancreatic-type tissue showed features very similar to normal pancreatic acinar tissue, such as well developed rough endoplasmic reticulum (RER), large numbers of mature zymogen granules, and a basally located nucleus. Protein A-gold imunocytochemical technique showed localization of amylase and trypsinogen over the zymogen granules and RER. These findings confirm that this tissue in the liver is morphologically and functionally identical to pancreatic acinar tissue.

59 citations


Journal ArticleDOI
TL;DR: It is proposed that the outer membrane blebs represent vehicles for excretion of unorganized sheath material and/or Mn2+-oxidizing protein produced by L. discophora.
Abstract: Leptothrix discophora strain SS-1 (ATCC 43182) is a Gram-negative, Mn2+-oxidizing, aerobic heterotroph which lost its sheath-forming ability after 18 months of cultivation on laboratory media. SS-1 possesses high 6-phosphogluconate dehydratase and KDPG aldolase activities, and a very low level of phosphofructokinase, indicating carbohydrate catabolism by the Entner-Doudoroff pathway. The strain is polarly flagellated, accumulates PHB up to 67% of its dry weight when grown in pyruvate-containing medium, and has a G+C content of 69.8 mol%. These properties indicate that L. discophora is essentially a pseudomonad which can form a sheath and oxidize Mn2+. Ultrastructural observations made before SS-1 lost its sheath-forming ability indicated two cell types. Short, flagellated, non-sheathed cells seen under the electron microscope probably corresponded to swarmer cells observed under phase-contrast microscopy. These cells contained plate organelles and PHB granules, and produced extracellular blebs approx. 25–50 nm in diameter. Larger sheathed cells also contained plate organelles, PHB granules, and blebs that were often sandwiched between the outer membrane and the sheath. Cells grown in the presence of added Mn2+ were surrounded by an extensive fibrillar matrix, rendered electron dense by precipitation of manganic oxide. The matrix was connected to various points of the cell by outer membrane evaginations or electron dense threads. We propose that the outer membrane blebs represent vehicles for excretion of unorganized sheath material and/or Mn2+-oxidizing protein produced by L. discophora.

Journal ArticleDOI
TL;DR: Protein bodies in the protoderm were smaller, denser-staining, and contained fewer crystalline inclusions than those in the parenchyma or procambium, and on a volume basis the p Karenchyma was shown to be 43% protein bodies, 25% lipid bodies, 15% cytoplasm, 7% cell wall, 4% intercellular space, 2% nuclei, and 4% other organelles (mitochondria and plast
Abstract: The seed of Washingtonia filifera (Lindl.) Wendl. is hemispherical and has a smooth testa. The embryo is located on the rounded side of the seed near the raphe. The embryo consists of a prominent single cotyledon, an epicotyl, and a small root apex. The shoot apex is oriented at a right angle to the long axis of the embryo and possesses 2 to 3 leaf primordia. The cotyledon functions as a storage organ and is composed of three cell types with similar ultrastructure. These three types-the parenchyma, protoderm, and procambium-can be distinguished on the basis of position, size, and shape. The procambial strands in the cotyledon consist of a ring of bundles grouped into two distinct sympodia and extend from beneath the shoot apical meristem to the tip of the cotyledon where they are situated very close to the surface. The most prominent organelles within all cell types are protein bodies, lipid bodies, and crystalline protein fibers. The protein bodies contain small crystalline inclusions which are presumed to be phytin. Protein bodies in the protoderm were smaller, denser-staining, and contained fewer crystalline inclusions than those in the parenchyma or procambium. On a volume basis, the parenchyma was shown to be 43% protein bodies, 25% lipid bodies, 15% cytoplasm, 7% cell wall, 4% intercellular space, 2% nuclei, and 4% other organelles (mitochondria and plastids).

Journal ArticleDOI
TL;DR: Ten instances of a white plaque of the lateral tongue unique to homosexual males and referred to as oral hairy leukoplakia were analysed ultrastructurally and showed evidence by electron microscopy of the presence of papilloma virus within koilocytotic nuclei.
Abstract: Ten instances of a white plaque of the lateral tongue unique to homosexual males and referred to as oral hairy leukoplakia were analysed ultrastructurally. The surface epithelial layer exhibited extracellular, intracellular and intranuclear penetration by hyphae of Candida albicans, sometimes accompanied by coccobacilli in the extracellular space. The subcorneal epithelial layer included koilocytoid ballooned cells which had a paucity of cytoplasmic organelles and displayed condensation and emargination of the chromatin. Cells that exhibited these nuclear changes were found to be infected by a herpes-type virus which was visualized by electron microscopy in all ten cases. Clusters of nucleocapsids (86-110 nm in diameter) occurred in the nuclei and enveloped virions (111-175 nm in diameter) occurred in the cytoplasm and extracellular spaces. Virions showed budding from the nuclear envelope. Bundles of tubular structures (20 nm diameter) arranged in parallel occurred in the cytoplasm of some koilocyloid cells. There was no evidence by electron microscopy of the presence of papilloma virus within koilocytotic nuclei.

Journal ArticleDOI
TL;DR: The ultrastructure of substance P-containing fibers in feline cerebral arteries was examined by combining substance P immunohistochemistry and electron microscopy and the number of mitochondria and organelles resembling vesicles appeared to increase in presumptive axon terminals.


Journal Article
TL;DR: This appears to be the first identification of light chain determinants in human interstitial para-amyloid deposits with the use of immunogold ultrastructural techniques in tissues prepared for electron microscopy by standard methods and stored as epoxy resin blocks.
Abstract: Kappa light chain determinants were identified by immunoelectron microscopy in nodular glomerulosclerotic lesions and systemic interstitial deposits from a man who died several years after the onset of proteinuric renal failure treated by hemodialysis. He developed adrenal and hepatic failure preterminally but not overt malignant myeloma. Specific labeling was most concentrated over the inner aspect of glomerular basement membrane and the mesangium, which suggested that the protein was nonfiltrable. Tubular basement membrane labeling was densest over the outer aspect, which suggested that the protein perfused from the interstitium rather than from the tubular lumen. We identified the source of the protein as a population of plasma cells present within bone marrow and renal interstitium; these showed specific immunogold labeling for kappa light chain protein over organelles concerned with protein synthesis, secretion, and storage. This appears to be the first identification of light chain determinants in human interstitial para-amyloid deposits with the use of immunogold ultrastructural techniques in tissues prepared for electron microscopy by standard methods and stored as epoxy resin blocks.

Journal ArticleDOI
01 Sep 1986-Planta
TL;DR: In dark-grown seedlings, phytochrome-labeling is distributed diffusely throughout the cytoplasm, but after a dark period of 3–4 h following red-light irradiation, these electron-dense structures disappear together with any specific labeling, suggesting a Pfr-induced aggregation of an unknown, phytochemicalbinding protein or proteins.
Abstract: We have analysed the intracellular localisation of phytochrome in oat coleoptile cells by electron microscopy and confirm and extend light-microscopical findings of previous authors. We used indirect immuno-labeling with polyclonal antibodies against 60-KDa phytochrome from etiolated oat seedlings, and a gold-coupled second antibody, on ultrathin sections of LR-white-embedded material. In dark-grown seedlings, phytochrome-labeling is distributed diffusely throughout the cytoplasm. Organelles and membranes are not labeled. After photoconversion of the red-absorbing form of phytochrome to the far-red absorbing form (Pfr) (5-min red light; 660 nm), the label is sequestered uniquely in electron-dense areas within the cytoplasm. These areas are irregularly shaped, are often located in the vicinity of the vacuole, are not surrounded by a membrane, exclude cellular organelles and ribosomes and are not found in dark-grown material; an immediate 5-min farred light pulse after the red light does not cause these structures to disappear. After a dark period of 3–4 h following red-light irradiation, these electron-dense structures disappear together with any specific labeling. We suggest a Pfr-induced aggregation of an unknown, phytochrome-binding protein or proteins.

Journal ArticleDOI
TL;DR: The ultrastructure of preovulatory human oocyte—cumulus complexes was described after inducing maturation by clomiphene, human menopousal gonadotropin (hMG), human chorionic gonad stimulant (hCG) treatment.
Abstract: The ultrastructure of preovulatory human oocyte—cumulus complexes was described after inducing maturation by clomiphene, human menopousal gonadotropin (hMG), human chorionic gonadotropin (hCG) treatment. The majority of the oocytes was at metaphase, II of meiosis, with a radially orientated spindle. The oocyte surface was covered by a multitude of microvilli. Cortical granules were nonuniformly distributed along the cortex. A cytoplasmic polarization was observed. The cytoplasmic organelles were in general uniformly dispersed, with the exception of a narrow segment within which cytoplasmic membranes and mitochondria formed clusters. The spirndle was usually found at the borderline between the two regions of the cytoplasm. The functional significance of this polarization is not yet known.


Journal Article
TL;DR: Several electron microscopy (EM) complementary techniques have been applied in the ultrastructural study of spaghetti as discussed by the authors, and three EM techniques were used to detect differences in protein and starch organization in relationship to spaghetti quality.

Journal ArticleDOI
TL;DR: The histoskeleton is involved in all epithelial activities but is not uniformly organized into identical cell patterns at the tissue level because activities are sequential and not synchronized in all cells, which suggests that the multiple functions of the epithelium may be mediated by the occurrence of several multicellular functional units within a single epithelial tissue.
Abstract: Comparative morphological studies on cytoskeletal patterns of sponge basal epithelium at the tissue level have been performed by diverse methods, including immunofluorescence microscopy, and scanning and transmission electron microscopy of stained whole mounts, thin sections or replicas. These methods give results consistent with each other and show the importance of actin assemblies, which function in addition to the microtubular system and in the absence of intermediate filaments. Actin microfilaments indeed are involved in the formation of cables and networks closely associated with the plasma membrane. Both the cables and the networks result from arrangements of microfilaments into bundles of variable size, and the two types of assembly are probably interconvertible. Microfilaments appear to be implicated in the establishment of spot desmosomes and as devices for cell-to-substratum attachment. Due to the desmosomal articulations from cell to cell, the actin cytoskeleton is framed throughout the complete epithelium. It supports the unitary nature of the entire tissue, which is constructed and functions as a whole. It therefore establishes the "histoskeleton" of basic epithelial tissues. The histoskeleton is involved in all epithelial activities but is not uniformly organized into identical cell patterns at the tissue level because activities are sequential and not synchronized in all cells. Similar cytoskeletal patterns exist only in groups of cells, and this suggests that, at a given time, the multiple functions of the epithelium may be mediated by the occurrence of several multicellular functional units within a single epithelial tissue.

Journal ArticleDOI
TL;DR: The cytology and ultrastructure of giant cells recruited to subcutaneously implanted isogeneic bone particles with similar features of osteoclasts in metaphyseal bone of young normal rats and mice are compared to confirm those of others that native osteoclast and multinucleated giant cells on dead bone particles are distinctly different with respect to both ultrast structure and mechanism of disruption of bone surfaces.
Abstract: The giant cells of soft tissues and those of mineralized tissues (osteoclasts) have distinctly different cell surface receptors and ultrastructural characteristics. Recently, the removal of dead bone particles in a subcutaneous environment has been described as a prototype of bone resorption, and a major issue is whether the giant cells that surround these ectopic bone implants and the processes involved in the disruption of bone surfaces are the same as those in the skeleton. We have compared the cytology and ultrastructure of giant cells recruited to subcutaneously implanted isogeneic bone particles with similar features of osteoclasts in metaphyseal bone of young normal rats and mice. Giant cells on surfaces of bone particles 2, 3, and 4 weeks after implantation were multinucleated, had a homogeneous, nonvacuolated cytoplasm, and had a bone surface interface unremarkable by light microscopy. In a few cells randomly distributed, small cytoplasmic vacuoles were present and large vacuoles were noted next to the bone surface at high magnification. By transmission electron microscopy, folded membrane configurations forming extensive interdigitations with adjacent cells were prominent features on most surfaces of giant cells. In instances where these interdigitations abutted bone surfaces, configuration resembling a ruffled border were noted, but these regions were always part of two different cells when examined at lower magnification or in serial sections. Breakdown of bone particles appeared to be by phagocytosis of small pieces and subsequent intracellular digestion in electron-dense cytoplasmic vacuoles. Osteoclasts from these same young animals were smaller with fewer nuclei, had cytoplasmic vacuoles concentrated next to bone surfaces, and had characteristic ruffled borders and clear zones. These results confirm those of others that native osteoclasts and multinucleated giant cells on dead bone particles are distinctly different with respect to both ultrastructure and mechanism of disruption of bone surfaces.

Journal ArticleDOI
01 Mar 1986-Placenta
TL;DR: The ultrastructural features of the umbilical vessels suggest an increased endothelial permeability, and it is suggested that transfer across the umbILical vessels may play a role in the formation of amniotic fluid.

Journal ArticleDOI
TL;DR: The results suggest that the initial stage of AChR aggregate assembly involves relatively subtle changes in the structure of the cell cortex and that the evolution of microaggregates to aggregates may require the formation of additional cytoskeletal and extracellular matrix structures.
Abstract: The ultrastructure of cultured rat myotubes was examined at stages in the initial assembly of acetylcholine receptor (AChR) aggregates in order to elucidate the role of cell-surface specializations in aggregate formation. Within 4-6 hr, embryonic brain extract (EBX) induces the formation of sites of AChR density elevated 5-9 X above that of surrounding regions, and the appearance of these aggregates is preceded by the formation of clouds of punctate microaggregates (Olek et al., 1983). A video image-intensification system was used to monitor this redistribution of fluorescently labeled AChR, and sites of aggregation were mapped on identified myotubes. After processing the cultures for electron microscopy, thin sections were taken through identified aggregate sites at various stages in assembly. Specializations, including a basal lamina, mound-shaped plasma membrane contours with occasional deep infoldings, and a subjacent dense cytoskeletal specialization, which tended to exclude other cytoplasmic organelles, were associated with newly formed aggregates found 4-6 hr after adding EBX to the cultures. Analysis of random thin sections through EBX-treated and untreated myotubes showed that the extent of specializations of the basal lamina and cytoplasm was approximately threefold greater in cells exposed to EBX for 4 hr, suggesting a concurrent, and possibly interdependent, organization of such specializations with AChR aggregate assembly. Examination of sections through clouds of microaggregates, which formed within 90 min, revealed mound-shaped plasma membrane contours and underlying cytoplasm depleted of organelles but relatively little basal lamina and submembrane cytoskeletal density. These results suggest that the initial stage of AChR aggregate assembly involves relatively subtle changes in the structure of the cell cortex and that the evolution of microaggregates to aggregates may require the formation of additional cytoskeletal and extracellular matrix structures.

Journal ArticleDOI
TL;DR: Ultrastructural observations are presented for some of the stages occurring during fertilization in Dionchus remorae (a gill parasite of Echeneis naucrates) and are believed to be the first published concerning a monogenean.
Abstract: Ultrastructural observations are presented for some of the stages occurring during fertilization in Dionchus remorae (a gill parasite of Echeneis naucrates) and are believed to be the first published concerning a monogenean. Fertilized female germ cells were found in the ovary. Several loops of the spermatozoon were present within the oocyte cytoplasm; the sperm nucleus became electron lucent and the parallel peripheral doublets of the axonemes became increasingly divergent. The cortical granules in the oocyte were not released immediately after penetration by the spermatozoon. The homogeneity apparently found in the oocyte ultrastructure and process of fertilization in the monogeneans and digeneans contrasts with the variety that exists in their sperm ultrastructure.

Journal ArticleDOI
01 Dec 1986-Botany
TL;DR: Serial sections for light microscopy or transmission electron microscopy of two Classopollis pollen tetrads show that the exine structure, except for the nexine, has radially arranged rodlike units interwoven with transverse subunits.
Abstract: Serial sections for light microscopy or transmission electron microscopy of two Classopollis pollen tetrads show that the exine structure, except for the nexine, has radially arranged rodlike units...

Journal Article
TL;DR: Immunohistochemistry showed that the actin content of the cytoskeleton could be preserved after detergent extraction and Detergent-extracted cells decreased their surface area when exposed to MgATP in a dose-dependent manner.
Abstract: An ultrastructural, immunohistochemical, and functional study was conducted on cultured bovine meshwork cells. Particular emphasis was placed on the organization of the cytoskeleton, and the cells were viewed either as whole cells or following detergent extraction. For ultrastructural examination, several modes of viewing were adopted, including a detector situated above the specimens collecting secondary electrons (SE), a detector situated beneath the specimen collecting transmitted electrons (STEM), and conventional transmission electron microscopy at 100 KV (TEM). In whole cell mounts, information was obtained about the organization of the cytoskeleton and its relationship to other cytoplasmic organelles. Extraction procedures removed much of the plasma membrane and most organelles. The nucleus and cytoskeleton remained and stress fibers were prominent. Immunohistochemistry showed that the actin content of the cytoskeleton could be preserved after detergent extraction. Detergent-extracted cells decreased their surface area when exposed to MgATP in a dose-dependent manner. The decrease in surface area was associated with disassembly of cytoskeletal stress fibers and was optimal with 1 mM MgATP. Whether or not the change in surface area could be considered a "contractile event" was discussed.

Journal ArticleDOI
TL;DR: The epidermis of the doliolaria larva of the Florometra serratissima is differentiated into distinct structures including an apical organ, adhesive pit, ganglion, ciliary bands, nerve plexus, and vestibular invagination, suggesting that they are functionally specialized in the larva.
Abstract: The epidermis of the doliolaria larva of the Florometra serratissima is differentiated into distinct structures including an apical organ, adhesive pit, ganglion, ciliary bands, nerve plexus, and vestibular invagination. All these structures possess unique cell-types, suggesting that they are functionally specialized in the larva, except the vestibular invagination that becomes the postmetamorphic stomodeum. The epidermis also contains yellow cells, amoeboid-like cells, and secretory cells. The enteric sac, hydrocoel, axocoel, and somatocoels have differentiated but are probably not functional in the doliolaria stage. Mesenchymal cells, around the enteric sac and coeloms, appear to be actively secreting the endoskeleton and connective tissue fibers. The nervous system is composed of a nerve plexus, ganglion, and sensory receptor cells in the apical organ. The apical organ is a larval specialization of the anterior end; the ganglion is located in the base of the epidermis at the anterior dorsal end of the larva. The nerve plexus underlies most of the epidermis, although it is more prominent in the anterior region. Here, processes from sensory receptor cells of the apical organ, as well as those from nerve cells, contribute to the plexus. These processes contain one or a combination of organelles including vesicles, vacuoles, microtubules, and mitochondria. The configuration of glyoxylic acid-induced fluorescence, revealing catecholamine activity, correlates to the apical organ, nerve cells, and nerve plexus. Morphological evidence suggests that the nervous system may function in initiation and control of settlement, attachment, and metamorphosis. The crinoid larval nervous system is discussed and compared to that found in other larval echinoderms.

Journal ArticleDOI
TL;DR: These findings identify those intracellular organelles that are functionally at the level of, or distal to, the sialyltransferase-containing membranes of the Golgi, and distinguish them from the pre-Golgi membranous structures.
Abstract: The subcellular distribution of sialic acid was determined at the ultrastructural level using Limax flavus agglutinin (LFA). This lectin, which is specific for N-acetylneuraminic acid and N-glycolylneuraminic acid, was covalently conjugated to horseradish peroxidase (HRP). The conjugates (LFA-HRP) were applied to aldehyde-fixed, saponin-permeabilized 3T3 cells in pre-embedding labeling electron microscopy. Peroxidase label was detected in a patchy distribution at the cell surface, and in plasma-membrane-coated pits, endocytic vesicles (receptosomes), multivesicular bodies, and lysosomes. Smooth-surfaced tubular and vesicular structures, similar to those that participate in membrane recycling, were labeled. In the Golgi complex, more than half of the cisternae contained label--typically only one cisterna on the cis side was unlabeled. Heavily labeled structures of the trans Golgi included a reticular membranous system with coated regions--50-80 nm diameter vesicular or pit-like profiles and larger coated vacuoles. Smooth 200-300 nm vacuoles were labeled on the trans side of the Golgi stack. Similar structures have been previously shown to participate in the exocytosis of plasma membrane and secretory glycoproteins from the Golgi stacks. These findings identify those intracellular organelles that are functionally at the level of, or distal to, the sialyltransferase-containing membranes of the Golgi, and distinguish them from the pre-Golgi membranous structures. The LFA-HRP conjugate is an indicator for this functional trans domain of the cell, and should be applicable for ultrastructural double-label experiments as a cis versus trans marker of the exocytic pathway.

Journal ArticleDOI
TL;DR: The ultrastructural features of the dormant, condensed state in resting cells of M, granulata are similar to those described for hypnospores and could provide a population of cells which could easily revert should environmental conditions become adverse.
Abstract: Detailed cytological changes that accompany the rejuvenation of resting cells of Melosira granulata were studied with the electron microscope. Dormant and viable cells that we previously classified as the condensed state generally contain definable chloroplasts, mitochondria, a nucleus and other cytoplasmic remnants. However, there appears to be a continuous cytoplasmic degradation spectrum and some cells which appear intensely colored with the light microscope have discontinuous chloroplast membranes and few other cytoplasmic remnants. Rejuvenation of viable dormant cells is initially accompanied by the accumulation of both lipids and polyphosphates. In the earliest stages of expansion, these storage products are dispersed throughout the cell. In later stages of expansion, the lipids appear to be coalesced into larger droplets which are easily identified at the light microscope level. The fully expanded stage is characterized by the normal complement of organelles and their arrangement at the periphery of the cells and central cytoplasmic bridge. These cells appear both anabolically and catabolically active as evidenced by the abundance of endoplasmic reticulum, ribosomes and secretory and lytic vesicles. Prior to cell division, both lipids and polyphosphates a re reduced or absent in the cells. The ultrastructural features of the dormant, condensed state in resting cells of M, granulata are similar to those described for hypnospores. A rejuvenation sequence that produces cytological features common to resting state formation could provide a population of cells which could easily revert should environmental conditions become adverse.