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Biomedical subjects

M Kagayama

Publications and source records attributed to M Kagayama.

At least 73 records · Page 4Linked to original sources
PubMed1989

A histochemical localization on Maclura pomifera lectin during osteogenesis.

Mandibular condyles of 4-week-old Wistar strain rats and mandibles of ICR strain mice from 14 days gestation stage to 2 days postnatal stage were used to investigate the localization of Maclura pomifera lectin (MPA) during two modes of osteogenesis. During endochondral ossification of the mandibular condyle, MPA was only localized at the peripheral regions of calcified cartilage after the destruction of chondrocyte lacunae. Bone extracellular matrix (ECM) was not reacted with MPA. In intramembranous ossification of mice mandibles, MPA was stained intensively in the early bone ECM. The intensity of the MPA reaction decreased during bone development. In both cases of osteogenesis, chondroclasts and osteoclasts showed the strong affinity to MPA. These results indicated that the time- and position-specific changes within ECM proceeded during osteogenesis and that MPA was the useful probe to detect chondroclasts and osteoclasts.

Animals↗
PubMed1989

[Lectin-binding sites in the growing end of rat incisors].

Tooth germs of rat incisors were examined by lectin-histochemistry in the portion from the apical end to enamel forming stage. Tissue sections were prepared from paraformaldehyde-fixed and paraffin-embedded tissues with or without EDTA-decalcification. They were stained with fluorescein-isothiocyanate-labeled (F- for short) lectins and observed by a fluorescent microscope. The boundary between inner enamel epithelia and dental papilla cells was stained with F-Con A, F-MPA and F-PNA. The boundary between the epithelia and dentin was stained with F-Con A and F-MPA. Stratum intermedium cells were stained with F-Con A, F-MPA and F-PNA, and were different in the time when they began to be stained with each lectin during their development. Distal cytoplasm of secretory ameloblasts and odontoblasts were stained with F-MPA and F-Con A, respectively. The staining with these lecting became stronger gradually from the apical to the incisal side. These results suggest that F-MPA and F-Con A are useful as a marker indicating the time when enamel and dentin begins to form, respectively. Distal cytoplasm of secretory ameloblasts was also stained with F-Con A and F-PNA. The odontoblastic layer was stained only with F-Con A, but the dental papilla was stained with F-Con A, F-MPA, and F-PNA. Stellate reticulum and outer enamel epithelia were stained with F-Con A and F-MPA. The comparison of the results from decalcified and non-decalcified tissues showed that the EDTA-decalcification scarcely affected these lectin bindings.

Amelogenesis↗
PubMed1988

A histochemical study on lectin binding in the immature enamel and secretory ameloblasts of rat incisors.

Four lectin-fluorescent marker conjugates (Con A-F, MPA-F, PNA-F, WGA-R) were used for visualizing their binding sites on tissue sections by fluorescent microscopy. The immature enamel, Tomes' processes and distal cytoplasm of ameloblasts were stained with MPA-F and WGA-R on paraformaldehyde-fixed and paraffin-embedded tissue sections. The MPA- and WGA-binding glycoconjugates seemed to be main components of the organic enamel matrix because of the intense fluorescence from the tissue sections. The central portion of distal cytoplasm of ameloblasts was stained with PNA-F but the immature enamel and Tomes' processes were not. This suggests the PNA-binding glycoconjugates to be intermediates during the process of modifying their oligosaccharide chains or to be elements of Golgi area. Tomes' processes, the distal cytoplasm and periphery of nuclei of ameloblasts were stained with Con A-F. The Con A-binding glycoconjugates except those localizing on Tomes' processes may also be intermediates and/or intracellular elements like the PNA-binding glycoconjugates. Cells of stratum intermedium were stained with Con A-F, MPA-F and WGA-R. Cells of stellate reticulum and outer enamel epithelium were stained with Con A-F and WGA-R. It was indicated that enamel proteins, major organic components of immature enamel, are highly possible candidates for the MPA- and WGA-binding glycoconjugates.

Ameloblasts↗
PubMed1987

Change of microtubular arrangement around centrioles in rat incisor odontoblasts during cell differentiation.

Three stages during cell differentiation of rat incisor odontoblasts were classified, and change of microtubular arrangement around centrioles in the odontoblasts was examined with three-dimensional analyses using serial ultrathin sections. In the undifferentiated odontoblasts, microtubules were observed to radiate from the pericentriolar area, whereas, in the differentiating odontoblasts, some microtubules became poorly related to the centrioles. In the differentiated odontoblasts, arrangement of most microtubules appeared to have a poor relationship to the centrioles. Throughout the differentiation of the odontoblasts, one of the centriolar pair was ciliated, and Golgi apparatus was invariably observed near the centrioles. The present study suggests that a pericentriolar area, or a centrosome, could function as a microtubule-organizing center (MTOC) in the undifferentiated odontoblasts, but their function might be attenuated during cell differentiation.

Animals↗
PubMed1985

Ultrastructure of mouse incisor ameloblasts after vascular perfusion with colchicine.

In order to revalue the effects of colchicine on incisor secretory ameloblasts, entire mice were perfused with Krebs solution supplemented with a buffer and amino acids, through the right common carotid artery. The normal ultrastructure of the cells was maintained for 2 h with the perfusate alone. When colchicine (0.3-3.0 micrograms/ml) was added to the perfusate, it induced ultrastructural changes, such as the loss of cytoplasmic microtubules, the loss of secretory granules in Tomes' process, the abnormal accumulation and secretion of secretory granules, disarranged Golgi apparatus and the fragmentation of rough endoplasmic reticulum. Vesicles (150-400 nm in diameter) resembling immature secretory granules also accumulated, the degree of accumulation depending on the duration of colchicine treatment. The accumulation of secretory granules and these vesicles suggests that the intracellular transport system was affected by colchicine but that the production of secretory granules was continuous throughout the experimental period. The present perfusion system has enabled us to treat ameloblasts with an agent that is a useful experimental tool for elucidating cell functions, despite being lethal to animals in vivo.

Ameloblasts↗
PubMed1985

Ultrastructure of secretory ameloblasts in puppies.

Four about 4-week-old puppies were fixed by perfusion; the secretory ameloblasts of the first molar tooth germs were observed with an electron microscope. The morphology of the puppy secretory ameloblast closely resembles that of man. In addition, the primary cilia and a pair of basal bodies were observed close to Golgi apparatus of the secretory ameloblast. Cytoplasmic microtubules radiated from the basal bodies. It is suggested that a pair of basal bodies may be the microtubule-organizing center of the secretory ameloblast. Further, melanocytes were present in the intermediate cell layer and aggregated melanosomes were present in the cytoplasm of both stratum intermedium cells and secretory ameloblasts.

Ameloblasts↗
PubMed1983

Light and electron microscopy of the effects of colchicine and vinblastine on maturing rat ameloblasts in vivo.

Both agents caused loss of ruffled membrane and microtubules. Ruffled membrane decreased with time after treatment with vinblastine (4 mg/kg) and almost disappeared 8 h after treatment with either colchicine (4 mg/kg) or vinblastine (4 mg/kg). In vinblastine-treated animals, the number of microtubules were estimated in cross-sections of two regions of both smooth-ended and ruffle-ended ameloblasts; one region was distal and the other juxta-nuclear. In smooth-ended ameloblasts, microtubules of both the distal and juxta-nuclear cytoplasm almost disappeared after 2 h of treatment. In ruffle-ended ameloblasts, microtubules decreased in distal cytoplasm between 2 and 8 h; microtubules in the juxta-nuclear cytoplasm disappeared after 2 h. Both agents caused structural alterations and dislocation of cell organelles. The Golgi apparatus, sometimes separated into two parts, moved towards the proximal cytoplasm and an unusual accumulation of small vesicles was found in the proximal cytoplasm. These findings suggest that formation of ruffled membranes is dependent on microtubular function.

Ameloblasts↗
PubMed1983

Three-dimensional visualization of Golgi-stained neurons by a projection X-ray microscope converted from a scanning electron microscope.

Trying to obtain the three-dimensional images of neuronal elements, Golgi-stained thick sections were examined by a projection X-ray microscope converted from a scanning electron microscope. An attachment unit for the projection X-ray microscope consists of a target holder, specimen stage and film cassette. Two kinds of target material, titanium and gold, were tested. The system was operated at 10 to 30 kV. The electron beam into the target was about 20 nA with the use of a pointed cathode. The stereopair of X-ray micrographs were taken by tilting the specimens. Quality and contrast of the X-ray micrograph taken with a titanium target was better than that with a gold target. The spatial resolution was estimated about 1 to 2 micrometers for 100 to 350 micrometers thick sections with a titanium target. Compared with the light microscope, strong penetrating ability of X-ray permitted to visualize the internal structures of optically opaque materials. Further, almost all objects were in focus in X-ray micrographs even for relatively thick sections (100 to 350 micrometers). The three-dimensional morphology of neurons and glial cells was demonstrated by a stereopair of X-ray micrographs.

Animals↗
PubMed1979

An electron microscopic study of the interaction between vesical epitherlium and E. Coli.

Interaction between rat bladder epithelium and Escherichia coli was observed using the transmission electron microscope. As a first step, the bacterial cell coat attaches to the cell coat of the luminal membrane. Then, the luminal membrane enfolds to envelope the bacterium and take it within the cytoplasm. The unit membranes covering the bacteria are destroyed and some of these bacteria are found to be deformed and probably dead in the cytoplasm. Finally, the superficial epithelial cells invaded by many bacteria are collapsed and desquamated into urine. However, these epithelia show a rather prompt recovery and form the normal three layers within 24 hr after inoculation. This experiment suggests one of the defense mechanisms of the vesical epithelium againts E. coli. It is likely that the onset of clinical cystitis may be prevented by the same mechanism during the occasional bacterial invasion of the bladder.

Animals↗
PubMed1977

Calcium and stimulus-secretion coupling in the mast cell: stimulant and inhibitory effects of calcium-rich media on exocytosis.

1. Isolated rat peritoneal mast cells incubated in Ca-free media for 2 h, with or without EDTA, and observed by phase-contact microscopy, became ;bubbled' in appearance when subsequently exposed to media rich in calcium (16-110 mM).2. Electron microscopy showed the response to be ;compound' exocytosis of the sort elicited by conventional mast cell secretagogues such as antigen (in sensitized cells) and 48/80.3. The response to Ca was inhibited by withdrawing glucose and adding dinitrophenol and was thus energy-dependent.4. Mg in similarly high concentration had no such stimulant effect on Ca-deprived cells, and excess Ca stimulated only after Ca deprivation.5. It is suggested that Ca deprivation may increase the permeability of the plasma membrane of the mast cell thereby allowing some Ca, when subsequently introduced in high concentration, to penetrate and activate exocytosis; and the results are considered further support for the postulated mediator function of Ca in stimulus-secretion coupling.6. Two inhibitory effects of calcium in high concentration were detected: (a) suppression of migration or expulsion of granules from the exocytotic pits within the cellular domain; and (b) diminished sensitivity to 48/80.

Animals↗
PubMed1974

Membrane potential and input resistance in acinar cells from cat and rabbit submaxillary glands in vivo: effects of autonomic nerve stimulation.

1. Membrane potential and input resistance measurements were made from acinar cells of cat and rabbit submaxillary glands in vivo, using intracellular glass micro-electrodes.2. The mean resting cell membrane potential was higher than previously reported, but ranged widely from -15 to -80 mV.3. Single shock electrical stimulation of the parasympathetic nerve fibres evoked characteristic potential changes. In some cases monophasic hyperpolarizations, in others biphasic responses (depolarization - hyperpolarization) were observed.4. The latency of the hyperpolarizing response was considerably longer (300-550 msec) than the latency of the biphasic response (about 150 msec).5. Hyperpolarizing and biphasic responses could be observed in the same cell at different levels of membrane potential. The initial depolarization of the biphasic response was dependent on the magnitude of the resting potential in such a manner that it was very small or absent at the lowest potentials and increased gradually with increasing level of the resting potential.6. Single-shock stimulation of the sympathetic nerve fibres to the gland did not evoke any response. In the cat, repetitive stimulation evoked hyperpolarizing or biphasic responses similar to those seen after repetitive stimulation of the parasympathetic nerve fibres. In the rabbit small hyperpolarizations were seen in a few cells only; mostly there was no response. Repetitive stimulation of the parasympathetic nerve fibres to the rabbit submaxillary gland evoked complex potential changes mostly of the depolarization-hyperpolarization type.7. Both single shock and repetitive stimulation of the parasympathetic nerve fibres evoked marked reductions in cell input resistance. In the hyperpolarizing cell type the conductance change sometimes preceded the potential change whereas they always occurred simultaneously in the biphasic cell type.8. It is concluded that both the hyperpolarizing and the biphasic secretory potentials are derived from the same type of acinar cells. The neurotransmitter released by the parasympathetic nerve endings (ACh) acts on the acinar cell membrane by increasing the ion permeability.

Animals↗