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 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

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

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

The morpologic change in the lens epithelial cell, which is metabolically the most active part of the lens, are closely related with the formation of the cataract. To evaluate the morphologic changes of lens epithelial cells in electric cataracts, the central 5-6mm of anterior lens capsule and adherent lens epithelial cells were obtained from patients with an electric cataract. One-half of the anterior lens capsule was examined with a light microscope using flat preparation, while the other half was examined with a transmission electron microscope. In the light microscopic findings, the lens epithelial cell, which has a hexagonal shape with monolayer in normal, lost its normal shape and was superimposed in pathologic areas. The electron microscopic findings showed that the number of mitochondria in the cytoplasm was increased. The rough endoplasmic reticulum in the cytoplasm was dilated and microfilaments were enriched. The dense bodies seen in the myofibrotic changes were observed lens capsule were also shown. The intracelluar vacuoles were seen in dying cells and growing of the cytoplasmic processes into the widened intercellular spaces were observed The authors recognized that the abnormal lens epithelial cells had altered cellular activity and that the cells in the patholoic areas had proliferated and degenerated.
Actin Cytoskeleton ; Cataract* ; Cytoplasm ; Endoplasmic Reticulum, Rough ; Epithelial Cells ; Epithelium* ; Extracellular Space ; Humans ; Mitochondria ; Vacuoles

In an attempt to evaluate the cardiotoxicity of bupivacaine, beating rate, tetrazolium MTT and lactate dehydrogenase activity were investigated in the medium containing bupivacaine for 24 hours after neonatal rat myocardial cells were cultured for 72 hours. Light and electron microscopic studies were also carried out. The results were as follows ; 1) Beating rate decreased dose-dependently, and beating cells were not observed over 10(-4) M concentration of bupivacaine. 2) MTT50 value was 0.32 ug/ml (1,000 uM). 3) The amount of lactate dehydrogenase released into the medium was 192% of control cells at 10(-3) M concentration of bupivacaine. 4. In light microscopy, myocardial cells were decreased in number dose-dependently, and showed a few cytoplasmic processes and lots of granules in cytoplasm at 10 M concentration of bupivacaine. 5. Electron microscopy of bupivacaine-treated cells showed smooth endoplasmic reticulum, destruction of mitochondria and Golgi apparatus and increase of vacuoles and dense bodies. It also showed dilatation of rough endoplasmic reticulum and loss of myofibrils. These results suggest that high concentration of bupivacaine (> or = 10(-4) M) induee remarkable toxicity on cultured rat myocardial cells.
Animals ; Bupivacaine* ; Cytoplasm ; Dilatation ; Endoplasmic Reticulum, Rough ; Endoplasmic Reticulum, Smooth ; Golgi Apparatus ; L-Lactate Dehydrogenase ; Microscopy ; Microscopy, Electron ; Mitochondria ; Myofibrils ; Rats* ; Vacuoles

To investigate the changing patterns of microfilament and microtubule arrangement and influence of myocardial cells and colchicines to microfilament and microtubule formation in cardiac endothelial cells the authors carried out indirect immunofluorescence stain for actin and tubulin with supernatant monoclonal antibodies. Secondary antibodies were IgG FITC conjugate. The results were summarized as follows. Fiberform reactions were stronger in the cells with many processes and spread cytoplasm and they became weaker after the endothelial cells formed monolayer. In the endothelial cells cocultured with myocardial cells the fiberform of the microtubule became less visible compared to control group but fiberform of the microtubule maintained strong intensity as endothelial cells formed monolayer. In the group treated with colchicines, there were no visible differences in microfilaments compared to control group but fiberform of microtubule revealed weaker intensity after colchicines treatment. The intensity of microtubule fiberform returned to control level after 2 days.
Actin Cytoskeleton ; Actins ; Antibodies ; Antibodies, Monoclonal* ; Cytoplasm ; Endothelial Cells* ; Fluorescein-5-isothiocyanate ; Fluorescent Antibody Technique, Indirect ; Immunoglobulin G ; Microtubules ; Tubulin

Melanocytes grown in the pure monolayer culture lack the three-dimentional organization and the cellular interactions that exist in vivo. These can be partially overcome by growing melanocytes together with other epidermal cells in cultured skin equivalent models. In this study, skin equivalents were prepared by seeding mixtures of cultured human keratinocytes and melanocytes in ratio 10 : 1 onto artificially constructed dermis. They were cultured in DMEM/F12 (1 : 1) for 4 days and then lifted to the air-liquid interface and maintained in DMEM/F12 (3 : 1) for 10 days. Histological and electronmicroscopic examinations of the cultured skin equivalants revealed a structure that closely resembled human interfollicular epidermis; 1. Melanocytes, were identified by positive staining with melanoma-specific antibodies (NKI/C3 and S-100 protein) and prominent cytoplasm with rich cell organelles, were located in the basal layer. 2. Melanocytes contained predominently early stage melanosomes and prominent Golgi apparatus. Mature melanins, were usually abundant in normal skin, were hardly seen both in melanocytes and in neighbouring keratinocytes. 3. Melanocytes were surrounded by keratinocytes but did not form intercellular junctions with them. 4. Keratinocytes were charaterized by microfilament bundles and intercellular junctions such as desmosomes and hemidesmosomes with neighbouring keratinocytes and artificial dermis. The melanocyte in the above skin equivalents had a strong resemblance to the one of normal human skin and therefore this model can be used as artificial skin for the transplantation and in the investigation of melanocytes' role to the UV stimuli.
Actin Cytoskeleton ; Antibodies ; Cytoplasm ; Dermis ; Desmosomes ; Epidermis ; Golgi Apparatus ; Hemidesmosomes ; Humans ; Intercellular Junctions ; Keratinocytes ; Melanins ; Melanocytes* ; Melanosomes ; Organelles ; Skin* ; Skin, Artificial

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