• Applied Microscopy
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• v.25 no.1
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• pp.48-64
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• 1995

Ultrastructure of nerves and their associated cells in the bronchiolar epithelium of the human fetal lung were studied with ultrastructural and immunohistochemical methods. The neuroendocrine cells were scattered along the basal part of non-ciliated respiratory epithelium and appeared as single cell (solitary neuroendocrine cell) or groups (neuroepithelial bodies). The solitary neuroendocrine cells were devoid of any detectable innervation, while the neuroepithelial bodies were associated with nerve ending containing morphologically afferent (sensory) and efferent (motor) intraepithelial terminals. The afferent nerve endings contained abundant mitochondria with long cristae. The efferent nerve endings were characterized by the presence of synaptic vesicles. Both types of nerve endings formed synaptic junction between nerve endings and neuroepithelial bodies cells. Serial sections of the intraepithelial nerves revealed that both morphologically afferent and efferent types of nerve endings may be formed by the same nerve fiber. By immunohistochemistry, bombesin and serotonin were localized in solitary neuroendocrine cells and neuroepithelial bodies of human fetal lung from various prenatal age groups. These results suggest that the neuroepithelial bodies cells of the human fetal lung have neuroreceptor function.

• Biomedical Science Letters
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• v.6 no.3
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• pp.165-170
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• 2000

Vacuolar (H$^{+}$)-ATPase (V-ATPase) is an intracellular protein which consists of multiple subunits. It carries out acidification by pumping protons in the cell. This enzyme has also been found in the synaptic vesicles and may play an important role in the neurotransmission. We cloned cDNA fragments encoding the 16 kDa subunit of V-ATPase from the rat brain by RT-PCR and PCR using total RNA or recombinant phage DNA as templates. They contained the full coding sequences (468 bp) and one nucleotide at 3' region turned out to be different (A to C) when compared to the liver counterpart. However, this polymorphic difference did not cause any significant change in the primary structure of the protein because both GCA and GCC code for alanine. Our study would contribute to the understanding of the function of 16 M)a V-ATPase in the brain and of the mechanisms of neurotransmission.

• International Journal of Oral Biology
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• v.43 no.3
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• pp.155-160
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• 2018

There exists very little information on the ultrastructure of substance P immunopositive (+) fibers in the human dental pulp, which may help in understanding the mechanism for substance P associated pulpal inflammatory pain. To address this issue, we investigated the presence of substance P+ fibers in the human dental pulp by light- and electron-microscopic immunohistochemistry. Light microscopy revealed that substance P+ fibers ran within neurovascular bundles in the radicular pulp and in the core of coronal pulp. They were also frequently present in the peripheral pulp. Substance P+ fibers showed beads like swellings interconnected by thin axonal strand, in a manner similar to bouton en passants and interconnecting axonal strand in the spinal cord. Electron microscopy revealed that almost all the substance P+ axons were unmyelinated. The axonal swellings of the substance P+ contained numerous clear round vesicles (40-50 nm in diameter) and many large dense-cored vesicles (80-110 nm in diameter) as well as many mitochondria. The vesicles and mitochondria were rarely observed in the thin axonal strand interconnecting the swellings. Intimate interrelationship or synaptic structure between the swellings of substance P+ axon and nearby pulpal cells or axons was not found. These findings suggest co-release of substance P and glutamate from the substance P+ pulpal axons and its action on nearby structures in a paracrine manner.

• International Journal of Oral Biology
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• v.41 no.3
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• pp.133-139
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• 2016

The ultrastructural parameters related to synaptic release of endings which are presynaptic to tooth pulp afferent terminals (p-endings) were analyzed to understand the underlying mechanism for presynaptic modulation of tooth pulp afferents. Tooth pulp afferents were labelled by applying wheat-germ agglutinin conjugated horseradish peroxidase to the rat right lower incisor, whereafter electron microscopic morphometric analysis with serial section and reconstruction of p-endings in the trigeminal oral nucleus was performed. The results obtained from 15 p-endings presynaptic to 11 labeled tooth pulp afferent terminals were as follows. P-endings contained pleomorphic vesicles and made symmetrical synaptic contacts with labeled terminals. The p-endings showed small synaptic release-related ultrastructural parameters: volume, $0.82{\pm}0.45{\mu}m^3$ ($mean{\pm}SD$); surface area, $4.50{\pm}1.76{\mu}m^2$; mitochondrial volume, $0.15{\pm}0.07{\mu}m^3$; total apposed surface area, $0.69{\pm}0.24{\mu}m^2$; active zone area, $0.10{\pm}0.04{\mu}m^2$; total vesicle number, $1045{\pm}668.86$; and vesicle density, $1677{\pm}684/{\mu}m^2$. The volume of the p-endings showed strong positive correlation with the following parameters: surface area (r=0.97, P<0.01), mitochondrial volume (r=0.56, P<0.05), and total vesicle number (r=0.73, P<0.05). However, the volume of p-endings did not positively correlate or was very weakly correlated with the apposed surface area (r=-0.12, P=0.675) and active zone area (r=0.46, P=0.084). These results show that some synaptic release-related ultrastructural parameters of p-endings on the tooth pulp afferent terminals follow the "size principle" of Pierce and Mendell (1993) in the trigeminal nucleus oralis, but other parameters do not. Our findings may demonstrate a characteristic feature of synaptic release associated with p-endings.

• Applied Microscopy
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• v.17 no.2
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• pp.41-54
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• 1987

This experiment was performed to investigate the acute and chronic effects of lead on cerebral cortex. In acute treatment, mouse were injected with lead acetate at dose of 0.3 mmole/kg body weight, and in chronic treatment, mouse were supplied 0.03 M lead acetate sol. in the place of water. After treatment, mouse were sacrificed at time intervals of 24, 48, 72, and 96 hours in acute treatment and at time intervals of 4 weeks and 8 weeks in chronic treatment. In acute treatment, acetylcholinesterase activity is reduced at 72 hours and recovered at 96 hours in homogenate, and reduced at 24 hours and recovered at 72 hours in crude synaptosomes. In chronic treatment, acetylcholinesterase activity is increased in young mouse but reduced in mother mouse. Ultrastructural changes were composed of swelling of Golgi apparatus, nerve terminals with diminished synaptic vesicles, and vacuolated myeline lamellae of myelinated axon.

• Applied Microscopy
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• v.25 no.4
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• pp.1-8
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• 1995

This study was performed to analyze the morphological changes of synapses during early postnatal periods. Neonatal rats were grouped by 3, 7, 14, 21, 28 and 42day old, and observed the ultrastructural pattern of the synapses in the neostriatum by transmission electron microscope. 1. The number of synapse, the length of postsynaptic thickening and the amount of synaptic vesicles markedly increase during postnatal development 2. The proportion of asymmetric and curved synapses gradually increase by developmental periods. From the above results, it is suggested that the size of synapse increase during post-natal period, and asymmetric synapse are formed from the symmetric type and curved synapse are formed from the plane type.

• BMB Reports
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• v.56 no.2
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• pp.90-95
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• 2023

Mitochondria are important organelles that regulate adenosine triphosphate production, intracellular calcium buffering, cell survival, and apoptosis. They play therapeutic roles in injured cells via transcellular transfer through extracellular vesicles, gap junctions, and tunneling nanotubes. Astrocytes can secrete numerous factors known to promote neuronal survival, synaptic formation, and plasticity. Recent studies have demonstrated that astrocytes can transfer mitochondria to damaged neurons to enhance their viability and recovery. In this study, we observed that treatment with mitochondria isolated from rat primary astrocytes enhanced cell viability and ameliorated hydrogen peroxide-damaged neurons. Interestingly, isolated astrocytic mitochondria increased the number of cells under damaged neuronal conditions, but not under normal conditions, although the mitochondrial transfer efficiency did not differ between the two conditions. This effect was also observed after transplanting astrocytic mitochondria in a rat middle cerebral artery occlusion model. These findings suggest that mitochondria transfer therapy can be used to treat acute ischemic stroke and other diseases.

• Applied Microscopy
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• v.25 no.2
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• pp.39-52
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• 1995

Pinealocytes in the lower vertebrate are known to have photoreceptive function. These photoreceptor cells have been characterized morphologically in various species of lower vertebrates. No such ultrastructural studies, however, were reported in fresh water turtle. The purpose of this study is to characterize the pinealocytes and the phylogenetic evoluton of these cells is discussed in terms of functional analogy. I. Light microscopy: The pineal body was divided into incomplete lobules by connective tissue septa containing blood vessels, and parenchymal cells were arranged as irregular cords or follicular pattern. In the lobules, glandular lumina were present and contained often densely stained materials. II. Electron microscopy: The pineal parenchyma had three categories of cells: photoreceptor cells, supportive cells and nerve cells. The photoreceptor cells had darker cytoplasm compared to the supportive cells, and the enlarged apical cytoplasm(inner segment) containing abundant mitochondria and dense cored vescles protruded into the glandular lumen in which lamellar membrane stacks(outer segment), dense membranous materials, and cilia were present. Some of these lamellated membrane stacks appeared to be dege-nerating while others were apparently newly formed. Constricted neck portion of the photoreceptor cells contained longitudinally arranged abundant microtubules. centrioles and cross-striated rootlets. Cell body had well developed Golgi apparatus, abundant mitochondria, dense granules($0.5{\sim}1{\mu}m$), dense cored vesicles($70{\sim}100nm$), and rough endoplasmic reticulum occasionally with dense material within its cisterna. Basal portion of the photoreceptor cells had basal processes often with synaptic ribbons, which terminate in the complicated zone of cellular and neuronal processes. Synatpic ribbons often made contact with the nerve processes and the cell processes of neighboring cells. In some instances, these ribbons were noted free within the basal process and were also present at the basal cell mem-brane facing the basal lamina. Obvious nerve endings with clear and dense cored vesicles were observed among the parenchymal cells. Photoreceptor cells of the snapping turtle pineal body were generally similar in fine structure to those of other lower verterbrates reported previously, and suggested to have both photoreceptive and secretory functions which were modulated by pinealofugal and pinealopedal nerves. The supportive cells were characterized by having large dense granules($0.3{\sim}1{\mu}m$), abundant ribosomes, well developed Golgi apparatus and rough endoplasmic reticulum. These cells were furnished with microvilli on the luminal cell surfaces, and often had centrioles, striated rootlets, abundant filaments especially around the nucleus, and scattered microtubules. Some supportive cells had cell body close to the lumen and extended a long process reaching to basal lamina, which appeared to be a glial cell. Nerve cells within the parenchyma were difficult to identify, but some large cells located basally were suspected to be nerve cells, since they had synaptic ribbon contact with photoreceptor cells.

• The Korean Journal of Pain
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• v.9 no.2
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• pp.326-335
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• 1996

Background: Though a number of studies have described the distribution of substance P(SP)-like immunoreactivity in the spinal cord, they have been focused on lamina I and II of the dorsal horn and there are little morphological studies on the topographic distribution and ultrastructure of the SP immunoreactive neurons especially in the ventral horn of the spinal cord. this study was conducted to identify distribution pattern of SP immunoreactive neurons and to difine the synaptic organization of their processes in ventral horn of the thoracic cord of the cat by preembbeding immunocytochemical method using SP antiserum. Methods: Five adults cats of either sex were used and deeply anesthetized by intramuscular injection of ketamine. After removal of the spinal cord, samples of thoracic cord were taken and placed in fresh fixative at $4^{\circ}C$ for 2 hours. Transverse sections $50{\mu}m$ thick were processed using the preembbeding immunocytochemical method and incubated consecutively in the specific primary antibody and the 10% normal goat serum, the rabbit anti-substance P antiserum, the biotin-labelled goat anti-rabbit IgG and finally the avidin-biotin-peroxidase complex. The processed tissue sections were throughly washed and stained in the black with 1% uranyl acetate. Section were examined on a electron microscope. Results: 1) SP immunoreactive neurons were observed in the gray matter around central canal. 2) In lamina I and II SP immunoreactivity was observed in both myelinated and unmyelinated nerve fibers, but in ventral horn only in the unmyelinated nerve fibers. 3) SP immunoreactive axon terminals with small round and large dense core vesicles made chemical synapses onto the dendrites of motor neurons in the ventral horn. Conclusion: SP immunoreactive neurons might play an important role in modulation of motor neurons in the ventral horn of the thoracic cord of the cat.

• Biomolecules & Therapeutics
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• v.29 no.6
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• pp.630-636
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• 2021

Eupafolin, a constituent of the aerial parts of Phyla nodiflora, has neuroprotective property. Because reducing the synaptic release of glutamate is crucial to achieving pharmacotherapeutic effects of neuroprotectants, we investigated the effect of eupafolin on glutamate release in rat cerebrocortical synaptosomes and explored the possible mechanism. We discovered that eupafolin depressed 4-aminopyridine (4-AP)-induced glutamate release, and this phenomenon was prevented in the absence of extracellular calcium. Eupafolin inhibition of glutamate release from synaptic vesicles was confirmed through measurement of the release of the fluorescent dye FM 1-43. Eupafolin decreased 4-AP-induced [Ca²⁺]_i elevation and had no effect on synaptosomal membrane potential. The inhibition of P/Q-type Ca²⁺ channels reduced the decrease in glutamate release that was caused by eupafolin, and docking data revealed that eupafolin interacted with P/Q-type Ca²⁺ channels. Additionally, the inhibition of calcium/calmodulin-dependent protein kinase II (CaMKII) prevented the effect of eupafolin on evoked glutamate release. Eupafolin also reduced the 4-AP-induced activation of CaMK II and the subsequent phosphorylation of synapsin I, which is the main presynaptic target of CaMKII. Therefore, eupafolin suppresses P/Q-type Ca²⁺ channels and thereby inhibits CaMKII/synapsin I pathways and the release of glutamate from rat cerebrocortical synaptosomes.