scholarly journals FINE STRUCTURE AND ORGANELLE ASSOCIATIONS IN BROWN ALGAE

1965 ◽  
Vol 26 (2) ◽  
pp. 523-537 ◽  
Author(s):  
G. Benjamin Bouck
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Brown Algae ◽  
Algal Cell ◽  
Plant Cells ◽  
Membrane Systems ◽  
Two Envelopes

The structural interrelationships among several membrane systems in the cells of brown algae have been examined by electron microscopy. In the brown algae the chloroplasts are surrounded by two envelopes, the outer of which in some cases is continuous with the nuclear envelope. The pyrenoid, when present, protrudes from the chloroplast, is also surrounded by the two chloroplast envelopes, and, in addition, is capped by a third dilated envelope or "pyrenoid sac." The regular apposition of the membranes around the pyrenoid contrasts with their looser appearance over the remainder of the chloroplast. The Golgi apparatus is closely associated with the nuclear envelope in all brown algae examined, but in the Fucales this association may extend to portions of the cytoplasmic endoplasmic reticulum as well. Evidence is presented for the derivation of vesicles, characteristic of those found in the formative region of the Golgi apparatus, from portions of the underlying nuclear envelope. The possibility that a structural channeling system for carbohydrate reserves and secretory precursors may be present in brown algae is considered. Other features of the brown algal cell, such as crystal-containing bodies, the variety of darkly staining vacuoles, centrioles, and mitochondria, are examined briefly, and compared with similar structures in other plant cells.

scholarly journals UNE FORME MICROTUBULAIRE ET PARACRISTALLINE DE RETICULUM ENDOPLASMIQUE DANS LES PHOTOCYTES DES ANNELIDES POLYNOINÆ

1966 ◽  
Vol 31 (1) ◽  
pp. 135-158 ◽  
Author(s):  
J. M. Bassot
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Contact Surface ◽  
Special Kind ◽  
The Other ◽  
Cytoplasmic Organelle ◽  
Specialized Form

Luminous cells of polynoid worm elytra have been examined by methods of electron microscopy, with special attention focused on the fine structure of photogenic grains. These cells send apical prolongations into the mid-part of the elytra. The plasma membrane is very sinuous, and a special kind of desmosome links two portions of the same membrane. In addition to all the organelles which can be found in nonluminescent epithelial cells of the elytra, numerous photogenic grains are contained in their cytoplasm. These grains are composed of undulating microtubules measuring 200 A in diameter; their disposition in the grain is highly regular, and the grains appear as paracrystals. At the borders of the grains, the walls of the microtubules are often in continuity with those of the endoplasmic reticulum and with the external membrane of the nuclear envelope. Because of this fact, the microtubules of the grains may be considered a cytoplasmic organelle, representing a specialized form of the endoplasmic reticulum. The microtubules permit the repartition, inside and outside their walls, of two different products, one being forty-three times more abundant than the other; thus, the contact surface, in comparison to the volume, is greatly increased. The induction of the luminous reaction by change in the permeability of the microtubule walls, allowing contact between the two substances, is suggested as a working hypothesis. There is an evolution of the grains along the axis of the photocytes. The grains are often surrounded by progressively increasing amounts of glycogen. Their paracrystalline disposition is altered at the apex of the luminous cells.

Complex envelope system. Membrane systems of plant cells

1974 ◽  
Vol 268 (891) ◽  
pp. 119-128 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Smooth Endoplasmic Reticulum ◽  
Plant Cells ◽  
Membrane System ◽  
Cellulose Microfibrils ◽  
Membrane Systems ◽  
Complex Envelope ◽  
Pectic Substances ◽  
The Matrix

The membrane system is made up of the nuclear envelopes, rough and smooth endoplasmic reticulum, Golgi apparatus and plasmalemma. Interconnexions between the various parts of the system are shown and these probably represent a flow of membrane from the endoplasmic reticulum through the Golgi apparatus to the plasmalemma. Membrane fractions have been isolated from broken cells and their function in the synthesis of polysaccharides established. It has been shown that the matrix polysaccharides of the wall (pectic substances and hemicelluloses) are formed within the membranes and that the pattern of synthesis of these polymers changes during differentiation of the cells. Cellulose microfibrils are probably synthesized at the plasmalemma which is formed by incorporation of membrane bounded vesicles from the Golgi apparatus. Thus the assembly of the polymers takes place either when the membrane is within the cytoplasm or when it is incorporated as the plasmalemma of the cell.

scholarly journals SYNTHESIS, MIGRATION, AND RELEASE OF PRECURSOR COLLAGEN BY ODONTOBLASTS AS VISUALIZED BY RADIOAUTOGRAPHY AFTER [3H]PROLINE ADMINISTRATION

1974 ◽  
Vol 60 (1) ◽  
pp. 92-127 ◽  
Author(s):  
Melvyn Weinstock ◽  
C. P. Leblond
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Phosphotungstic Acid ◽  
Secretory Granules ◽  
Low Ph ◽  
Collagen Fibrils ◽  
Dentin Collagen ◽  
Odontoblast Process ◽  
High Radioactivity

The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30–40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline. At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains. At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280–350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules. Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process. At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process. It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.

scholarly journals The fine structure produced in cells by primary fixatives 2. Potassium dichromate

1965 ◽  
Vol s3-106 (73) ◽  
pp. 15-21
Author(s):  
JOHN R. BAKER
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Nuclear Membrane ◽  
Osmium Tetroxide ◽  
Potassium Dichromate ◽  
Potassium Dichromate Solution ◽  
Zymogen Granules ◽  
Mouse Pancreas

The exocrine cells of the mouse pancreas were fixed in potassium dichromate solution, embedded in araldite or other suitable medium, and examined by electron microscopy. Almost every part of these cells is seriously distorted or destroyed by this fixative. The ergastoplasm is generally unrecognizable, the mitochondria and zymogen granules are seldom visible, and no sign of the plasma membrane, microvilli, or Golgi apparatus is seen. The contents of the nucleus are profoundly rearranged. It is seen to contain a large, dark, irregularly shaped, finely granular object; the evidence suggests that this consists of coagulated histone. The sole constituent of the cell that is well fixed is the inner nuclear membrane. The destructive properties of potassium dichromate are much mitigated when it is mixed in suitable proportions with osmium tetroxide or formaldehyde.

Ultrastructural Observations of Cell Wall Regeneration Around Isolated Tobacco Protoplasts

1974 ◽  
Vol 14 (2) ◽  
pp. 439-449
Author(s):  
J. BURGESS ◽  
E. N. FLEMING
Keyword(s):  
Electron Microscopy ◽  
Heavy Metal ◽  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cell Wall Regeneration ◽  
Membrane Systems ◽  
Tobacco Protoplasts ◽  
Wall Formation ◽  
Wall Regeneration ◽  
Wall Growth

The process of cell wall regeneration around cultured protoplasts isolated from tobacco mesophyll has been examined by electron microscopy. The initially formed wall contains 2 components which stain with conventional heavy metal stains. The first consists of un-branched fibres, at first oriented at right angles to the plasmalemma surface. As wall growth proceeds the fibres lengthen and assume an orientation parallel to the plasmalemma. It seems probable that this component is cellulose. The second component of the wall is more amorphous and more densely stained. It is most frequently seen in situations where leaching of materials into the medium would be expected to be minimal. The endoplasmic reticulum and the plasmalemma are the only membrane systems which appear to contribute towards wall formation. No pattern of structure has been detected to explain the orientation or method of synthesis of the microfibrillar part of the wall.

scholarly journals Light and dark cells in the lumbar sensory ganglia of pre and post-hatching domestic fowl

1988 ◽  
Vol 46 (1) ◽  
pp. 3-5
Author(s):  
Claudio A. Ferraz de Carvalho ◽  
Ciro F. da Silva
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Domestic Fowl ◽  
Sensory Ganglia ◽  
Dark Cells ◽  
Junctional Complexes ◽  
Functional Features

Clear and dark satellite cell classes were identified by electron microscopy in the lumbar sensory ganglia of domestic fowl in 8 pre and 4 post-hatching stages of development. Some cytologic differences found between the two classes relating to the rough-endoplasmic reticulum, ribosomes, Golgi apparatus and junctional complexes suggest the existence of distinct functional features for both types of satellite cells.

scholarly journals OBSERVATIONS ON THE DEVELOPMENT OF ERYTHROCYTES IN MAMMALIAN FETAL LIVER

1962 ◽  
Vol 14 (2) ◽  
pp. 235-254 ◽  
Author(s):  
Joseph A. Grasso ◽  
Hewson Swift ◽  
G. Adolph Ackerman
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Cell Size ◽  
Marked Decrease ◽  
Fetal Liver ◽  
Hepatic Parenchyma ◽  
Hemoglobin Synthesis ◽  
Hepatic Cells ◽  
Eventual Loss

The fine structure of the erythrocyte during development in rabbit and human fetal liver has been studied. A morphologic description of representative erythropoietic cells and their relationship to the hepatic parenchyma is presented. Erythrocyte development was accompanied by a decrease in nuclear and cell size, fragmentation and eventual loss of nucleoli, and progressive clumping of chromatin at the nuclear margin. Mitochondria, endoplasmic reticulum, and Golgi elements decreased in size or abundance and eventually disappeared. Ribosome concentration initially increased, but subsequently diminished as the cytoplasm increased in electron opacity, probably through the accumulation of hemoglobin. Similar dense material, interpreted to be hemoglobin, infiltrated the nuclear annuli and, in some cases, appeared to extend into the interchromatin regions. There was a marked decrease in the number of annuli of the nuclear envelope. Possible relationships between nucleus and cytoplasm and of RNA to hemoglobin synthesis are discussed. In rabbits, erythroid and hepatic cells were separated by a 200 to 400 A space limited by the undulatory membranes of the respective cells. Membranes of adjacent erythropoietic cells were parallel and more closely apposed (100 to 200 A). In humans, relationship between various cells exhibited wide variation. Ferritin particles were observed within forming and formed "rhopheocytotic" vesicles.

Development of the lateral palatal brush in larvae of Aedes aegypti (L.) (Diptera: Culicidae)

1990 ◽  
Vol 68 (7) ◽  
pp. 1454-1467 ◽  
Author(s):  
K. M. Fry ◽  
S. B. McIver
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Aedes Aegypti ◽  
Rough Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Fourth Instar ◽  
Muscle Fibres ◽  
Final Length

Light and electron microscopy were used to observe development of the lateral palatal brush in Aedes aegypti (L.) larvae. Development was sampled at 4-h intervals from second- to third-instar ecdyses. Immediately after second-instar ecdysis, the epidermis apolyses from newly deposited cuticle in the lateral palatal pennicular area to form an extensive extracellular cavity into which the fourth-instar lateral palatal brush filaments grow as cytoplasmic extensions. On reaching their final length, the filaments deposit cuticulin, inner epicuticle, and procuticle sequentially on their outer surfaces. The lateral palatal crossbars, on which the lateral palatal brush filaments insert, form after filament development is complete. At the beginning of development, the organelles involved in plasma membrane and cuticle production are located at the base and middle of the cells. As the filament rudiments grow, most rough endoplasmic reticulum, mitochondria, and Golgi apparatus move to the apex of the epidermal cells and into the filament rudiments. After formation of the lateral palatal brush filaments and lateral palatal crossbars, extensive organelle breakdown occurs. Lateral palatal brush formation is unusual in that no digestion and resorption of old endocuticle occurs prior to deposition of new cuticle. No mucopolysaccharide secretion by the lateral palatal brush epidermis was observed, nor were muscle fibres observed to attach to the lateral palatal crossbars, as has been suggested by other workers.

Ultrastructural Studies on the Effects of Korean Panax Ginseng on the Theca Interna of Rat Ovary

1979 ◽  
Vol 07 (04) ◽  
pp. 333-344 ◽  
Author(s):  
Moo Rim Byung
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Panax Ginseng ◽  
Lipid Droplets ◽  
Ultrastructural Studies ◽  
Dense Bodies ◽  
Rat Ovary ◽  
Theca Interna ◽  
Morphologic Changes

An investigation was conducted to delineate the fine structure of steroid-producing ovarian theca interna cells following administration of Korean Panax ginseng to rats for 60 days. The cytoplasmic changes were observed in the ginseng-treated theca interna cells, increased number, size and density of the mitochondria, and increased size of the smooth surfaced endoplasmic reticulum, the rough surfaced endoplasmic reticulum and the Golgi apparatus. The nucleus and nucleolus were slightly enlarged and increased numbers of dense bodies were seen whereas lipid droplets were decreased in number. The changes may result from hyperfunction of the steroid-producing cells. Morphologic changes seen may represent stimulating effects on the steroid-producing cells of the theca interna in ginseng-treated animals.

Temperature Effects on Formation and Fine Structure of Brassica napus Leaf Waxes

1976 ◽  
Vol 24 (3) ◽  
pp. 309 ◽  
Author(s):  
DJ Armstrong ◽  
MI Whitecross
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Brassica Napus ◽  
Growth Temperature ◽  
Temperature Effects ◽  
Structural Changes ◽  
Leaf Waxes ◽  
Surface Waxes ◽  
Biochemical Level

Incorporation of 1-14C-palmitic acid, a precursor of leaf waxes, into leaf strips of Brassica napus was examined by thin section autoradiography and electron microscopy. Label was found to be associated with mitochrondria, Golgi vesicles and endoplasmic reticulum of epidermal cells, and also with the outer epidermal wall across which cuticular lipids are expected to migrate. Variations in growth temperatures produced structural changes in surface waxes as previously reported but no specific correlation could be found between changes in surface fine structure and variations in subcellular morphology. It is concluded that variations in wax fine structure, as influenced by growth temperature, resulted from effects at the biochemical level.

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