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.

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.

Ultrastructure of Solitary Enchondromas

1984 ◽  
Vol 9 (1) ◽  
pp. 95-97 ◽  
Author(s):  
MARILYN L. ZIMNY ◽  
I. REDLER
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Cell Types ◽  
Transmission Electron ◽  
The Matrix ◽  
Small Bones ◽  
Dying Cells ◽  
Myelin Figures

Solitary enchondromas obtained from the small bones of the hand were studied with transmission electron microscopy. Three cell types were seen as follows: (1) young looking, active cells with extensive dilated rough endoplasmic reticulum and well defined Golgi and mitochondria; (2) older looking, degenerating cells with dilated rough endoplasmic reticulum, well defined Golgi, glycogen masses, vacuoles containing tropocollagen, lipid and myelin figures; and (3) dying cells showing loss of cell membrane and lysosomal-like bodies. A young chondroblastic cell may try to mature, become a normal chondrocyte that produces normal matrix but it does not succeed and dies. Enchondromal cells are not capable of forming tropocollagen or synthesizing proteoglycans for the matrix.

A Study of the early stages of infection with the tipula iridescent virus

Parasitology ◽  
1958 ◽  
Vol 48 (3-4) ◽  
pp. 459-462 ◽  
Author(s):  
Kenneth M. Smith
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Thin Sections ◽  
Iridescent Virus ◽  
Early Stages ◽  
Primary Body ◽  
Gradual Development

Ultra-thin sections and electron microscopy have been used in a study of the empty membranes which occur in the fatbody cells of the larva of T. paludosa infected with the Tipula Iridescent Virus (TIV).It has been observed that these empty membranes are most numerous in the early stages of infection. Later an apparent ‘primary body’, which may be threadlike in its initial stages, develops in the centre of the membrane. This primary body seems to increase in size until the membrane is filled, and the various steps in this process can easily be seen.It is suggested that the formation of the empty membranes and the apparent gradual development of their contents are the means by which the virus multiplies.The remarkable resemblance between the empty virus membranes and the endoplasmic reticulum is pointed out.

scholarly journals Involvement of the Endoplasmic Reticulum in Peroxisome Formation

2003 ◽  
Vol 14 (7) ◽  
pp. 2900-2907 ◽  
Author(s):  
Hans J. Geuze ◽  
Jean Luc Murk ◽  
An K. Stroobants ◽  
Janice M. Griffith ◽  
Monique J. Kleijmeer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Dendritic Cells ◽  
Three Dimensional ◽  
Matrix Proteins ◽  
Peroxisomal Membrane ◽  
Present Evidence ◽  
Transporter Protein ◽  
Atp Binding Cassette Transporter ◽  
The Matrix

The traditional view holds that peroxisomes are autonomous organelles multiplying by growth and division. More recently, new observations have challenged this concept. Herein, we present evidence supporting the involvement of the endoplasmic reticulum (ER) in peroxisome formation by electron microscopy, immunocytochemistry and three-dimensional image reconstruction of peroxisomes and associated compartments in mouse dendritic cells. We found the peroxisomal membrane protein Pex13p and the ATP-binding cassette transporter protein PMP70 present in specialized subdomains of the ER that were continuous with a peroxisomal reticulum from which mature peroxisomes arose. The matrix proteins catalase and thiolase were only detectable in the reticula and peroxisomes. Our results suggest the existence of a maturation pathway from the ER to peroxisomes and implicate the ER as a major source from which the peroxisomal membrane is derived.

scholarly journals Ultrastructure and oil secretion in Hiptage sericea Hook

2014 ◽  
Vol 62 (1-2) ◽  
pp. 17-20 ◽  
Author(s):  
K. Arumugasamy ◽  
K. Udaiyan ◽  
S. Manian ◽  
V. Sugavanam
Keyword(s):  
Endoplasmic Reticulum ◽  
Inclusion Bodies ◽  
Smooth Endoplasmic Reticulum ◽  
Lipid Bodies ◽  
Starch Grains ◽  
Early Stages ◽  
The Matrix ◽  
Plasmalemma Invaginations

The oil secreting glands of <i>Hiptage sericea</i> Hook. consist of three regions: epithelial, sub-epithelial and sub-glandular. In early stages, the oil secreting cells are characterized by the presence of plastids with starch grains and electron translucent vesicles, mitochondria, rER, polysomes, small vacuoles, numerous lipid bodies and well-defined nucleus with nucleolus. Later, the accumulation of plastoglobuli and inclusion bodies occur in the matrix of the plastid. Tubular, smooth endoplasmic reticulum begins to appear in the cytoplasm. With the onset of secretion, the osmiophilic contents of plastids which appear as electron dense, round droplets move-into cytoplasm and often occur in the region of the plasmalemma invaginations. However, in matured glands the lipid bodies disappear from the cytoplasm. The size of the vacuoles increases and are filled with electron opaque substance. Similar substances are also found in the sub-cuticular spaces as well as outside the cuticle.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

Modification of Pineal Ultrastructure by Exogenous Hormones

1967 ◽  
Vol 25 ◽  
pp. 170-171
Author(s):  
R. A. Turner ◽  
A. E. Rodin ◽  
D. K. Roberts
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
List Type ◽  
Type Number ◽  
Pregnant Rats ◽  
Gonadal Atrophy ◽  
Pineal Ultrastructure

There have been many reports which establish a relationship between the pineal and sexual structures, including gonadal hypertrophy after pinealectomy, and gonadal atrophy after injection of pineal homogenates or of melatonin. In order to further delineate this relationship the pineals from 5 groups of female rats were studied by electron microscopy:ControlsPregnant ratsAfter 4 weekly injections of 0.1 mg. estradiol benzoate.After 8 daily injections of 150 mcgm. melatonin (pineal hormone).After 8 daily injections of 3 mg. serotonin (melatonin precursor).No ultrastructural differences were evident between the control, and the pregnancy and melatonin groups. However, the estradiol injected animals exhibited a marked increase in the amount and size of rough endoplasmic reticulum within the pineal cells.

The Structure and Development of Microbodies in the Fat Body and other Tissues of an Insect (Calpodes Ethlius)

1970 ◽  
Vol 28 ◽  
pp. 148-149
Author(s):  
M. Locke ◽  
J. T. McMahon
Keyword(s):  
Electron Microscopy ◽  
Liquid Crystals ◽  
Fat Body ◽  
Competitive Inhibitor ◽  
Dense Core ◽  
Urate Oxidase ◽  
Blood Proteins ◽  
Free Base ◽  
The Core ◽  
The Matrix

The fat body of insects has always been compared functionally to the liver of vertebrates. Both synthesize and store glycogen and lipid and are concerned with the formation of blood proteins. The comparison becomes even more apt with the discovery of microbodies and the localization of urate oxidase and catalase in insect fat body.The microbodies are oval to spherical bodies about 1μ across with a depression and dense core on one side. The core is made of coiled tubules together with dense material close to the depressed membrane. The tubules may appear loose or densely packed but always intertwined like liquid crystals, never straight as in solid crystals (Fig. 1). When fat body is reacted with diaminobenzidine free base and H2O2 at pH 9.0 to determine the distribution of catalase, electron microscopy shows the enzyme in the matrix of the microbodies (Fig. 2). The reaction is abolished by 3-amino-1, 2, 4-triazole, a competitive inhibitor of catalase. The fat body is the only tissue which consistantly reacts positively for urate oxidase. The reaction product is sharply localized in granules of about the same size and distribution as the microbodies. The reaction is inhibited by 2, 6, 8-trichloropurine, a competitive inhibitor of urate oxidase.

Copper Localization in Cirrhotic Rat Liver by Scanning Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 38-39 ◽  
Author(s):  
J. C. Russ ◽  
E. McNatt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Copper Acetate ◽  
Lead Citrate ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Electron Mode ◽  
Scanning Electron

In order to study the retention of copper in cirrhotic liver, rats were made cirrhotic by carbon tetrachloride inhalation twice weekly for three months and fed 0.2% copper acetate ad libidum in drinking water for one month. The liver tissue was fixed in osmium, sectioned approximately 2000 Å thick, and stained with lead citrate. The section was examined in a scanning electron microscope (JEOLCO JSM-2) in the transmission electron mode.Figure 1 shows a typical area that includes a red blood cell in a sinusoid, a disse, and a portion of the cytoplasm of a hepatocyte which contains several mitochondria, peribiliary dense bodies, glycogen granules, and endoplasmic reticulum.

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