Cytological studies on physodes in the vegetative cells of Cystoseira stricta Sauvageau (Phaeophyta, Fucales)

1980 ◽  
Vol 41 (1) ◽  
pp. 209-231
Author(s):  
L. Pellegrini
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cell Walls ◽  
Higher Plants ◽  
Close Association ◽  
Chloroplast Envelope ◽  
Osmiophilic Granules ◽  
Cytological Changes ◽  
Ultrastructural Characteristics ◽  
Secondary Lysosomes

Physodes have been recognized in meristodermic and promeristematic cells by correlated light- and electron-microscope investigations using different fixation procedures. They are vesicles which contain an osmiophilic material of phenolic nature. Their content changes in appearence according to the fixative used. Osmiophilic deposits are often associated with coiled and disturbed lamellar formations. It has been possible to distinguish several ultrastructural stages which occur during the secretion of the content of the physodes, namely: a chloroplast accumulation and exudation, and a reticular transport to accumulation vacuoles where materials undergo evolution or hydrolysis. Inside plastids, osmiophilic granules are found in close association with thylakoid stacks. They may contain the polyphenolic precursors of physodes, though this has not yet been proved by electron-microscopy procedures. They are expelled from plastids to the chloroplast endoplasmic reticulum. The mechanism of transfer through the chloroplast envelope endoplasmic reticulum. The mechanism of transfer through the chloroplast envelope remains to be elucidated. Lytic activities have been reported inside physodes which might thus act in the same way as the secondary lysosomes of animals and higher plants. Occasionally, the physode content seems to be excreted from the cytoplasm to the cell walls by exocytosis after the probable fusion of plasmalemma and tonoplast. These cytological changes, observed in the vegetative apex of a brown alga, recall some ultrastructural characteristics of the secretory processes described in various glandular tissues of higher plants and which consist of the synthesis, the transport and the elimination of an exudate of flavonic, terpenic or lipophenolic nature.

Extrusion of Nuclear Material During Oogenesis in Blatta Orientalis

1962 ◽  
Vol s3-103 (62) ◽  
pp. 141-145
Author(s):  
R.A. R. GRESSON ◽  
L. T. THREADGOLD
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Close Association ◽  
Nuclear Material ◽  
Blatta Orientalis ◽  
Nucleolar Material

That nucleolar material is extruded to the cytoplasm of the young oocyte of Blatta orientalis is confirmed by means of electron microscopy. The nucleolus and nucleolar extrusions are shown to contain RNA. In addition to the nucleolar extrusions, vesicle-like structures originate in the nuclear membrane and from there pass into the cytoplasm where they become indistinguishable from elements of the endoplasmic reticulum. When the nucleolar extrusions reach the cytoplasm they increase in size, come into close association with a few mitochondria, and migrate towards the periphery of the cell. It is concluded that the emission of material from the nucleolus and the passage of vesicles from the nuclear membrane to the cytoplasm are necessary prerequisites for the process of vitellogenesis.

Electron Microscopy Observations on a Spontaneous Mastocytoma in a Dog

1964 ◽  
Vol 50 (5) ◽  
pp. 375-402 ◽  
Author(s):  
Natale Pennelli ◽  
Luigi Mazzarella ◽  
Wim Misdorp
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Methyl Methacrylate ◽  
Toluidine Blue ◽  
Golgi Region ◽  
Specific Granules ◽  
Different Types ◽  
Ultrastructural Characteristics

The ultrastructure of a dog mastocytoma examined with the electron microscope after fixation in glutaraldehyde, post-fixation in osmiumtetroxide and butyl-methyl methacrylate embedding is described. The ultrastructural characteristics with particular regard to the submicroscopic morphology of specific granules were studied in details, also with the aid of comparative observations on thick sections stained by Giemsa and toluidine blue. On the basis of their observations, the authors describe the following characteristics of neoplastic mastcells: microvilli, a well-developed Golgi region, centrioles, mithocondria, ribosomes, endoplasmic reticulum and 4 different types of granules. Other mastcells, with various degree of regressive phoenomena, had almost no microvilli, multiple interruptions of plasma membrane, mithocondrial swelling as well as vacuolar and fibrillar aspect of the cytoplasm. The morphology of different types of intracytoplasmic granules is discussed also in the light of parallel observations made by other authors. Expulsions of granules were not observed. The hypothesis of the phospholipidic nature of the lamellar component of granules is suggested.

scholarly journals The Fine Structure of the Wheat Scutellum Before Germination

1972 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
JG Swift ◽  
TP O'brien
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Coat Protein ◽  
Storage Protein ◽  
Cell Walls ◽  
Lipid Droplets ◽  
Light And Electron Microscopy ◽  
Ground Substance ◽  
Nuclear Chromatin

The structure of the cells of the scutellar epithelium and parenchyma is described and illustrated by light and electron microscopy of air-dry grains and compared with that seen in grains soaked for 3 hr. In the air-dry state, nuclear chromatin is strongly aggregated, mitochondria and plastids appear to be intact, endoplasmic reticulum is present but not abundant, and dictyosomes cannot be readily identified. The ground substance contains an abundance of free ribosomes which appear to coat protein bodies, lipid droplets, and mitochondria. In material soaked only for 3 hr, endoplasmic reticulum and dictyosomes are apparent, the nuclear chromatin has dispersed, and some mobilization of storage protein appears to have begun in the scutellar epithelium. No differences in fine structure of other organelles or in the cell walls could be detected.

The subcellular organization of stomatal initials in sugarcane leaves: the guard and subsidiary mother cells

1977 ◽  
Vol 55 (22) ◽  
pp. 2801-2809 ◽  
Author(s):  
A. P. Singh
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Close Association ◽  
Preprophase Band ◽  
Central Position ◽  
Guard Mother Cell ◽  
Subcellular Organization ◽  
Guard Mother Cells ◽  
Mother Cells ◽  
Preprophase Bands

The subcellular organization of guard and subsidiary mother cells in sugarcane leaves was examined by electron microscopy. Guard and subsidiary mother cells assume a characteristic shape before mitosis and contain variable numbers of mitochondria, proplastids, dictyosomes, and cisternae of rough endoplasmic reticulum. In guard mother cells, the nucleus occupies a central position, whereas in subsidiary mother cells, the nucleus is located toward one end of the cell, near the guard mother cell. Microtubules are found in both guard and subsidiary mother cells and are either closely grouped to form defined preprophase bands or randomly dispersed between the nucleus and the preprophase bands. Many of the dispersed microtubules occur in close association with the nucleus in both guard and subsidiary mother cells. Possible functions for these preprophase microtubules are discussed in relation to their organization in the preprophase band, their orientation, and their distribution within guard and subsidiary mother cells.

The origin and fate of the nuclear membrane in meiosis

1960 ◽  
Vol 152 (948) ◽  
pp. 353-366 ◽  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Phase Contrast ◽  
Close Association ◽  
Early Prophase ◽  
Daughter Cells ◽  
Nuclear Membranes ◽  
Contrast Microscopy ◽  
Surrounding Membrane

The behaviour of the nuclear membrane during meiotic division in locust spermatocytes has been studied by electron microscopy. Preliminary observations were made on living cells from locusts, grasshoppers and beetles by phase-contrast microscopy and on snail and newt spermatocytes by electron microscopy. The mitochondria come into close association with the nuclear membrane during prophase and are often clustered round regions of degenerating nuclear membrane. The mitochondrial membranes sometimes appear to be fused with the nuclear membrane, and gaps in the latter are often found near mitochondria. Lamellar stacks are found in the cytoplasm during early prophase and closely resemble the nuclear membrane in the same cells ; they are generally annulate in spermatogonia and primary spermatocytes butsmooth-walled in secondary spermatocytes. There is evidence that the stacks arise by repeated folding of the nuclear membrane and become converted into endoplasmic reticulum. After division, the daughter cell chromosomes are at first devoid of a surrounding membrane. Elements of the endoplasmic reticulum accumulate between the mitochondria and gradually surround the chromosomes. These elements fuse to form a continuous double nuclear membrane. It is suggested that the nuclear membrane, endoplasmic reticulum and cell membrane are composed of the same material, which can be transformed into different structures according to the needs of the cell. The nuclear membrane is converted into endoplasmic reticulum during division and stored in the cytoplasm . The new nuclear membranes in the daughter cells are formed by the fusion of elements of the endoplasmic reticulum.

scholarly journals Normal rabbit alveolar macrophages. II. Their primary and secondary lysosomes as revealed by electron microscopy and cytochemistry.

1976 ◽  
Vol 144 (4) ◽  
pp. 920-932 ◽  
Author(s):  
B A Nichols
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Rough Endoplasmic Reticulum ◽  
Alveolar Macrophages ◽  
Digestive Enzymes ◽  
Acid Hydrolases ◽  
Secondary Lysosomes ◽  
Enzymatic Machinery ◽  
Cytochemical Markers

In this investigation, vacuoles containing tubular myelin proved to be digestive compartments with cytochemical reactivity for acid phosphatase and arylsulfatase. These cytochemical markers identify the secondary lysosomes, known to contain enzymes capable of hydrolyzing phospholipids like surfactant. Therefore, it appears that alveolar macrophages possess the enzymatic machinery for the degradation of the tubular myelin found in their digestive vacuoles. Although it thus appears evident that alveolar macrophages participate in the turnover of surfactant, the quantitative significance of this route of disposal is undetermined. This investigation has also established that acid hydrolases, so prominently displayed in the secondary lysosomes, are also localized in the rough endoplasmic reticulum and in Golgi-endoplasmic reticulum-lysosomes (GERL). Moreover, small vesicles which are produced from GERL serve as primary lysosomes in transporting digestive enzymes to the vacuoles.

Exploring Scots pine fibre development mechanisms during TMP processing: Impact of cell wall ultrastructure (morphological and topochemical) on negative behaviour

Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Dinesh Fernando ◽  
Geoffrey Daniel
Keyword(s):  
Electron Microscopy ◽  
Energy Consumption ◽  
Scots Pine ◽  
Cell Walls ◽  
Middle Lamella ◽  
Electrical Energy ◽  
Electrical Energy Consumption ◽  
Fibre Cell ◽  
Fibre Development ◽  
Ultrastructural Characteristics

Abstract A study was carried out aiming at understanding the fundamental reasons for different fibre behaviour exhibited by Norway spruce and Scots pine causing large energy consumption differences during thermomechanical pulping (TMP). Ultrastructural characterization of TMP fibres and shives, which were sampled from the two wood species after primary refining, was performed using scanning electron microscopy, transmission electron microscopy (TEM) and TEM-immunogold labelling for their morphological and topochemical properties. As expected, pine wood chips needed higher electrical energy consumption to be refined to a given Canadian Standard Freeness and it produced inferior strength properties compared to spruce. Electron microscopy (EM) observations indicated that the mechanisms of fibre development during primary refining of pine and spruce were different. The two stages of pine fibre separation and development were not concurrent. Results indicated that pine fibre defibration/fracture occurred predominantly through the compound middle lamella/S1 interphase or through the S1 layer producing lesser amounts of shives during the primary refining stage than spruce. In contrast, spruce fibres defibrated mainly through the S2 layer. Detailed EM observations on shives and pulp fibres from TMP revealed the ultrastructural characteristics associated with pine fibre cell walls. Morphological and topochemical features of the S1 layer, S1/S2 interphase, such as lignin and galactoglucomannan distribution across cell walls were explored. The ultrastructural properties are discussed in relation to the TMP parameters (i.e., electrical energy consumption) and strength data. It is concluded that ultrastructural characteristics of Scots pine fibre cell walls govern the different fibre development mechanisms and explain the negative response of this wood during TMP processing.

Effects of Glyphosate on Chloroplast Ultrastructure of Quackgrass Mesophyll Cells

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 22-25 ◽  
Author(s):  
W. F. Campbell ◽  
J. O. Evans ◽  
S. C. Reed
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Chloroplast Ultrastructure ◽  
Cellular Damage ◽  
Chloroplast Envelope ◽  
Mesophyll Cells ◽  
Subsequent Formation ◽  
Complete Disruption ◽  
Standard Techniques

Phytotoxicity of glyphosate (N-(phosphonomethyl) glycine), applied at 0, 0.56, 1.12, 1.68, 2.24 and 4.49 kg ai/ha to uniform, naturally growing quackgrass, [Agropyron repens (L.) Beauv.] plants, was studied with the electron microscope. Visible damage (yellowing of the leaves) to the plants was observed at the 2.24 and 4.49 kg ai/ha dosage rates within 72 hr. Similar damage became evident 120 hr after treatment at the 0.56 to 1.68 dosages. Leaf discs (1 mm in diameter) were harvested at 24, 48, 96, and 192 hr and prepared for electron microscopy by standard techniques. Cellular damage could be detected at all dosage rates as early as 24 hr after treatment. The type of damage observed was partial to complete disruption of the chloroplast envelope, and swelling of the rough endoplasmic reticulum (RER) with a subsequent formation of vesicles. With loss of integrity of the envelope, the chloroplast became completely disrupted with increased time. Other organelles within the cell were also destroyed.

THE DEVELOPMENT OF CYTOPLASMIC BRIDGES IN VOLVOX AUREUS

1966 ◽  
Vol 44 (12) ◽  
pp. 1697-1702 ◽  
Author(s):  
T. Bisalputra ◽  
Janet R. Stein
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Higher Plants ◽  
Early Stages ◽  
The Matrix ◽  
Cytoplasmic Bridges

The structure and development of cytoplasmic bridges connecting adjoining cells in Volvox aureus coenobia is demonstrated by electron microscopy. The cytoplasmic connections originate from incomplete cell division. In the early stages, mitochondria and other smaller organelles may move freely from one cell to the next. The cytoplasmic bridges then stretch as the cells separate from each other during maturation of the colony. When they are fully stretched, only endoplasmic reticulum and ribosomes are found in these cytoplasmic strands. The nature of these cytoplasmic connections is discussed and it is concluded that they should be distinguished from plasmodesmata of higher plants and the structures should be called simply "cytoplasmic bridges". It is also reported that the matrix of the colonial wall is derived from the dictyosome activity during the coenobium development.

Ultrastructural study and cytochemical investigation, by means of enzyme–gold complexes, of the fungus Ascocalyx abietina

1987 ◽  
Vol 65 (1) ◽  
pp. 168-181 ◽  
Author(s):  
Nicole Benhamou ◽  
G. B. Ouellette
Keyword(s):  
Endoplasmic Reticulum ◽  
Ultrastructural Study ◽  
Cell Walls ◽  
Thick Wall ◽  
Gold Complexes ◽  
Cytochemical Investigation ◽  
Ultrastructural Characteristics ◽  
Parallel Arrays ◽  
Fibrillar Network

The fungus Ascocalyx abietina (Lagerberg.) Schlaepfer-Bernhard, the scleroderris canker agent of conifers, is composed of a regularly septate mycelium, often branched at divergent angles. All fungal cells appear delimited by a thick wall surrounded by a dense fibrillar network. Peculiar ultrastructural characteristics of this fungus were observed, such as irregular nuclei with multishaped blebs and endoplasmic reticulum oriented in definite parallel arrays. Presence of single or multiple endocells was frequently observed. In some instances, gaps were present in the walls of enclosing cells where the cytoplasmic contents had escaped. Amylase, chitinase, β-galactosidase, lipase, and cellulose–gold complexes were used to localize various substances in A. abietina cells. With such complexes N-acetyl-D-glucosamine, β-galactosides, and lipids were detected in the cell walls, while glycogen deposits were found to occur in cytoplasmic electron-transparent bodies. The present work presents the ultrastructural features of A. abietina and adds to some of the cytochemical aspects recently reported.

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