Bile canaliculi is closely related to the cytoskeleton; actin filament web, microtubules and cytokeratin intermediate filaments. To understand how cytoskeletal alteration affects bile canalicular structure, the investigators injected cytochalasin B and colchicine into mice intraperitoneally to inhibit the polymerization of actin filaments and microtubules respectively, and observed the structural changes of bile canaliculi and hepatocytes with transmission and scanning electron microscopes. Bile canaliculi were dilatated and microvilli were decreased in number and length after injection of cytochalasin B and colchicine. Some bile canaliculi branched irregularly after colchicine treatment. Actin filament web in the canalicular ectoplasm was disrupted leaving granular zone after cytochalasin B treatment, but was intact after colchicine treatment. Intermediate filament bundles located at angles to the canalicular membrane appeared after colchicine treatment. Intercellular junctions delimiting bile canaliculi were intact after colchicine treatment, however were disrupted after cytochalsin B treatment. Focal junctions resembling desmosome were formed between microvilli after colchicine treatment. In both cytochalasin B and colchicine treated groups, lumen of rough endoplasmic reticulum were dilated, Golgi apparatus became prominent, and lipid droplets were appeared in the cytoplasm. These results suggest that both intact actin filaments and microtubules are necessary to keep the structural integrity of bile canaliculi.
Actin Cytoskeleton ; Animals ; Bile Canaliculi* ; Bile* ; Colchicine* ; Cytochalasin B* ; Cytoplasm ; Cytoskeleton ; Desmosomes ; Endoplasmic Reticulum, Rough ; Golgi Apparatus ; Hepatocytes* ; Humans ; Intercellular Junctions ; Intermediate Filaments ; Keratins ; Liver* ; Membranes ; Mice* ; Microtubules ; Microvilli ; Polymerization ; Polymers ; Research Personnel

The cytoskeleton consists of 3 filamentous components: intermediate filaments, microtubules, and actin filaments. Actin filaments continuously assemble and disassemble far out of equilibrium to adapt cells in response to external stimuli. Actin filaments organization and dynamic are controlled by a multitude of actin-binding proteins including actin-bundling proteins. L-plastin, expressed abundantly in lymphocytes and monocytes, is an actin-bundling protein that roles in immune defense and in metastatic invasion of cancer cells. The actin-bundling activity of L-plastin is regulated not only by intracellular calcium concentration, but by phosphorylation of Ser5. The actin-bundling activity of L-pastin decreases by increased calcium concentration but is promoted by phosphorylation of Ser5. The morphology changes and motility of cells requires continuous remodeling of actin filaments which demands the sensitive nature of L-plastin to Ca2+-signal, phosphorylation of Ser5, and probably additional regulation. This review briefly describes the structure and regulation of L-plastin, and roles for L-plastin in cancer invasion and in macrophages.
Actin Cytoskeleton ; Calcium ; Cytoskeleton ; Intermediate Filaments ; Lymphocytes ; Macrophages* ; Microfilament Proteins ; Microtubules ; Monocytes ; Phosphorylation

The purpose of this study was to investigate changes in the shape and ultrastructure of the articular disc of the rat mandibular joint with aging. Mechanical stress applied to the articular disc changes during neonatal, suckling, juvenile, adult and senile stages. Mandibular joints of 6 groups of rats(l-, 7-, 17-, 27-, 55-day and over-1-year groups) were removed en bloc and processed for light and electro microscopic study. The changes in the shape of articular disc were examined by light microscope in each group. Structural and ultrastructural changes in the articular disc were examined by light and electron microscope in each group. The results were as follows : In the 1-day and 7-day groups, the articular disc was long and slender in shape and the articular disc was not fitted with the shape of the mandibular fossa and condyle. However, after that time, the anterior and posterior portions of the articular disc were more bulged and the middle portion was shorter and biconcave. Thus the articular disc was well fitted with the shape of the mandibular fossa and condyle. The cell density decreased with aging. In the 1-day and 7-day groups, the Golgi apparatus, rough endoplasmic reticulum and free ribosome, which are involved in the synthesis of intracellular and extracellular matrix, were developed. In the 17-day, 27-day and 55-day groups, not only the cell organelles involved in the synthesis of the intracellular and extracellular matrix but also the cell organelles involved in the remodeling of the extracellular matrix(i.e., finger-like cell process, lysosome and mitochondria)were well developed. With advancing age, intracytoplasmic microfilaments were more accumulated and condroid cells increased. In the over-1-year group, the majority of cells of the articular disc were chondroid cells. The majority of cytoplasmic compartment were filled with intracytoplasmic microfilaments and cell organelles were not developed. Therefore, metabolic activities of the cell was markedly reduced and cells contained structures enduring mechanical stress, and cells which were in the process of degeneration were observed occasionally.
Actin Cytoskeleton ; Adult ; Aging* ; Animals ; Cell Count ; Cytoplasm ; Endoplasmic Reticulum, Rough ; Extracellular Matrix ; Golgi Apparatus ; Humans ; Joints* ; Lysosomes ; Organelles ; Rats* ; Ribosomes ; Stress, Mechanical

The effects of morphine HCI on the rat mesenteric mast cells were studied with the electron microscopy. The materials were prepared for electron microscopy by osmium tetroxide fixation and embedding in Epon. The rat mesenteric mast cells showed no distinct morphological changes due to morphine HCl, but the mast cell granlues were changed in various ways. For instance, they formed dusters, showed granular lysis, and an appearance of electron transparency. Frequently, some granules appeared in the extracellular space and the boundary of the granules was not evident. From the results mentioned above, it was suggested that rat mesenteric mast cell granules were affected by morphine HCl in the shape, the granular matrix, and the granular boundaries.
Animal ; Cell Nucleus/ultrastructure ; Cytoplasm/ultrastructure ; Cytoplasmic Granules/drug effects ; Cytoplasmic Granules/ultrastructure ; Golgi Apparatus/ultrastructure ; Male ; Mast Cells/drug effects ; Mast Cells/ultrastructure* ; Mesentery/drug effects ; Mesentery/ultrastructure* ; Microscopy, Electron ; Mitochondria, Muscle/ultrastructure ; Morphine/pharmacology* ; Rats

Nocodazole is an anticancer agent that acts on microtubules or filaments. HeLa, Hep G2, A549, L929 and NIH/3T3 cell lines were cultivated in alpha-MEM with 3micrometer or 30micrometer nocodazole. To elucidate the associations between nocodazole`s antitumor actions and these effects, the influences of nocodazole on the cellular morphology and the organelles involving synthesis, secretion and destruction of proteins were investigated under light and electron microscopes. The changes of intermediate filaments such as pancytokeratins and vimentins that maybe suggest antimetastatic action of nocodazole were observed using immunocytochemical technique, PAP at light microscopic level. Rounded or micronucleate cells were induced by treatment with 3micrometer and 30micrometer nocodazole for 2 hours to 4 days. Multimicronucleate cells appeared in experimental groups of all cell lines. Nuclear foldings occurred in cells of experimental groups treated with nocodazole for 2-3 days. The numerical increases of rough endoplasmic reticulum were observed in HeLa cells treated with nocodazole for 3 days and the dilatation or numerical increases in L929 cells treated with nofodazole for 1-3 days. The fragmentations or dispersion of Golgi complex were observed in cells treated with nocodazole for 1-3 days. The amount of filaments increased in cells treated with nocodazole for 1-3 days. The number of lysosomes increased in cells treated with nocodazole for 1-3 days. The number of liposomes also increased in Hep G2 cells treated with 30micrometer nocodazole for 3 days and in 3micrometer & 30micrometer, 3 days group of 3T3 cells. The amount of pancytokeratins and vimentins increased in cells treated with nocodazole for 1-3 days. Taken together, depolymerization of microlubules was induced by nocodazole, and then the organization of cells was disintegrated. As a result, the rounded cells, the cells having multimicronuclei, and the changes of golgi complexes occurred. But there were relatively no great changes of rough endoplasmic reticulum. The amount of intermediate filaments that maintain the differentiated states of cells increased by nocodazole treatment. It was suggested that morphological changes of cells could be used in evaluation of actions of nocodazole. Especially, the increase of amount of intermediate filaments by nocodazole changed cells of each cell line from undifferentiated state to differentiated, and therefore the author hope that the changes in amount of intermediate filaments provide an important clue in anticancer and antimetastatic actions of nocodazole.
3T3 Cells ; Animals ; Cell Line ; Dilatation ; Endoplasmic Reticulum, Rough ; Golgi Apparatus ; HeLa Cells ; Hep G2 Cells ; Hope ; Humans ; Intermediate Filaments ; Liposomes ; Lysosomes ; Mice ; Microtubules ; Nocodazole* ; Organelles ; Vimentin

This study was performed to investigate the subcellular changes of rat atrial muscle cells by immobilization stress. Sprague -Dawley rats weighting 200 gm were immobilized in small round plastic tube for 2, 6, 12, and 24 hours respectively. The atrial tissue obtained from each animals were observed by transmission electron microscopes. In the heart of rat subjected 2 hours immobilization stress no significant morphological changes were found in electron microscopy, similarly as in control animal. After 6 and 12 hours immobilization stress, the following electron -microscopic changes of atrial myocytes were observed at the swelling of mitochondrial matrix with disturbance in cristea, focal loss of cytoplasmic matrix, vacuoles with myeline -like structure, apoptotic changes of myocytes, focal widening of intercalated disc interspace and lysis of myofibrils. After 24 hours immobilization stress, very small sized mitochondria, similarly as small sized secretory granules and various sized granules are observed in the perinuclear region of atrial myocytes. Atrial specific granules are moved centripetally toward the central region of the atrial myocytes after immobilization stress. Above results will be aid in understanding the structures of atrium with dual function of blood circulation and endocrine, and in research of modulation of secretory granules in atrial muscle cells.
Animals ; Blood Circulation ; Cytoplasm ; Heart ; Immobilization* ; Microscopy, Electron ; Mitochondria ; Muscle Cells* ; Myelin Sheath ; Myofibrils ; Plastics ; Rats* ; Secretory Vesicles ; Vacuoles

BACKGROUND: Intermediate filaments as well as microtubule and microfilament are major components of cytoskeleton of human cells. Melanocytes have vimentin intermediate filament, which have not been well investigated as other cytoskeletons, especially in their function. OBJECTIVE: The purpose of this study was to observe the motile characteristics of vimentin intermediate filament in living B16 melanoma cells. METHODS: The motile properties of vimentin intermediate filament have been studied in living B16 melanoma cells using green fluorescent protein(GFP). cDNA expressing GFP-vimentin fusion protein was cloned and transfected into living B16 melanoma cells. Living cells were observed under fluorescent microscope and confocal microscope. Time-lapse images were collected and analysed. RESULTS: GFP-vimentin is incorporated into the endogenous vimentin networks. Time-lapse observations of vimentin fibrils demonstrate that they are constantly changing their configurations. Intersecting points of vimentin fibrils, or foci, frequently move towards or away from each other, indicating that the fibrils can lengthen or shorten. Fluorescence recovery after photobleaching shows that bleach zones across fibrils rapidly recover their fluorescence. During this recovery, bleached zones frequently move, indicating translocation of fibrils. Short filamentous structures('squiggle') are also seen actively translocating. Melanosomes also are changing their position back-and-pro constantly. They are co-localized very well with kinesin molecules in B16 melanoma cells. CONCLUSION: The vimentin intermediate filament and melanosomes in B16 melanoma cells have very active movement, which seem to have close relation with kinesin motor proteins.
Actin Cytoskeleton ; Clone Cells ; Cytoskeleton ; DNA, Complementary ; Fluorescence ; Fluorescence Recovery After Photobleaching ; Humans ; Intermediate Filaments* ; Kinesin ; Melanocytes ; Melanoma, Experimental* ; Melanosomes ; Microtubules ; Vimentin*

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

The Kingdom fungus has a unique structure and organization. Recent advances in electron microscopy and use of specific cytochemical technique enable the ultrastructures to be visualized. The hypha is a tube-like structure with a rigid wall, containing a moving slug of protoplasm. Hypha grows only at the tapered apical tip region, which is called extension zone. Extreme tip area has apical vesicle cluster which is responsible for tip growth. Unique fungal structure, Spitzenk rper, is thought to be a central region of the apical vesicle cluster. Most hyphal structures except the species belong to Zygomycetes have septa. But the septum is not completely blocked and it has different types of opening pores. The simple septal pores with Woronin bodies, which are found in Ascomycetes and Deuteromycetes, can be plugged in two different mechanisms. During normal differentiation the pores become occluded by a gradual deposition of plugged material. Loss of cytoplasm from damaged hyphae can be reduced and blocked by the rapid occlusion of septal pores by Woronin bodies or hexagonal crystal bodies. Septal sealing in Basidiomycetes which have dolipore septum is made by the rapid formation of electron-dense pore plugs. The shape of the fungal cell is the shape of fungal wall. Fungal walls appear to be composed of layers, which are thought to merge into one another to form one structure. The cytoskeleton consists of microtubules and microfilaments with motor proteins, and they seems to act together in the fungal cells.
Actin Cytoskeleton ; Ascomycota ; Basidiomycota ; Cytoplasm ; Cytoskeleton ; Fungal Structures ; Fungi ; Gastropoda ; Hyphae ; Microscopy, Electron ; Microtubules ; Mitosporic Fungi