• Applied Microscopy
• /
• v.31 no.1
• /
• pp.1-8
• /
• 2001

The morphological features of neuronal dendritic spines are changed their shapes, sizes and density in response to physiological or pathological conditions . Therefore, exact analysis of spines warrants understanding of neuronal function. The size of the spine is at the borderline of resolution with light microscopy. High voltage electron microscopy Provide excellent resolution of the spines with proper stain techniques thanks to its higher resolution and penetration power. We evaluated more effective staining method for observing dendritic spines after labeling Purkinje cells with anti-calbindin 28 kD immunohistochemistry or Golgi staining methods. 4 fm thickness sections were observed with high voltage electron microscopy and some morphometric analyses were performed. Both Golgi staining and immunohistochemistry revealed the detail structures of the Purkinje cell such as soma, dendrites, and dendritic spines. High voltage electron micrographs with Golgi staining provide more precise morphology and are easy to measure. Average density of spine is $24.5{\pm}3.6/10{\mu}m$ and its length is $1.12{\pm}0.22{\mu}m$. For quantitative analysis of the spines, high voltage electron, micrographs with Golgi staining are more effective. This preliminary result is expected to be useful for further study of spine plasticity in various conditions.

• Applied Microscopy
• /
• v.25 no.1
• /
• pp.65-74
• /
• 1995

An immunocytochemical study of GABA-positive neuronal elements was performed at the electron microscopic level to examine subcellular distribution of the inhibitory neurotransmitter in the dog basilar pons. Electron-dense reaction product was observed in neuronal somata and dendritic processes. One or more unlabeled axon terminals made asymmetric synaptic contacts with these GABAergic somatic and dendritic profiles. A large number of GABA-positive axon terminals were also observed. They made symmetric as well as asymmetric synaptic contacts with unlabeled dendritic profiles. In axo-axonic synapses, postsynaptic axon-like processes were consistently GABA-immunoreactive. These observations suggest that the inhibitory local circuit neurons in the dog basilar pons play a major role in cerebro-ponto-cerebellar circuitry by integrating various afferent inputs and conveying them into the cerebellar cortex and the deep cerebellar nuclei.

• Applied Microscopy
• /
• v.27 no.1
• /
• pp.57-70
• /
• 1997

The distribution of glutamatergic synaptic structures in the dog basilar pons was investigated at the ultrastructural level using monoclonal antibodies against fixative-modified glutamate. Electron-dense reaction product was densely localized at the perinuclear region in the neurenal somata and often observed along the microtubules located within the dendritic processes. One or more unlabelled axon terminals made asymmetric synaptic contacts with glutamate-immunoreactive dendritic profiles. In audition, reaction product was observed either within axonal processes surrounded by myelin sheath or axon terminals. Immunoreactive axon terminals made asymmetric synaptic contact either with unlabelled or labelled dendritic profiles. These observations provided an anatomic evidence of how this excitatory neural element might perform its function in a multisynaptic pathway involving glutamatergic afferents to the basilar pons, glutamate-immunoreactive pontocerebellar projection neurons, and the glutamate-positive granule cells of the cerebellar cortex.

• Journal of Oral Medicine and Pain
• /
• v.30 no.1
• /
• pp.87-106
• /
• 2005

In order to evaluate the mechanism of transmission as well as processing of sensory information originating from low-threshold mechanoreceptor in oral and maxillofacial region at primary synaptic region of trigeminal nervous system, vibrissa afferent fibers of adult cat were labeled with intra-axonal HRP injection. Serial sections containing labeled boutons were obtained from the piece of trigeminal interpolar nucleus. Under electron microscope, total 30 labeled boutons were observed, and ultrastructural characteristics, frequency of occurence, synaptic organizations of vibrissa afferent terminals were analysed. The results were as follows: 1. Labeled boutons contained clear, spherical synaptic vesicles with diameter of 45$\sim$55nm. They formed asymmetrical synapse with dendrites showing definite postsynaptic density, larger synaptic cleft, multiple synaptic structures at various regions. With unlabeled axon terminals(p-ending) containing polymorphic synaptic vesicles, they formed symmetrical synapse showing indefinite postsynaptic density and narrower synaptic area. 2. Each labeled bouton formed 1 to 15 synapses, the average of 4.77$\pm$3.37 contacts per labeled bouton, with adjacent neuronal profiles. Relatively complex synaptic organization, which formed synapses with more than 5 neuronal profiles, was observed in a large number(46.7%, n=14) of labeled boutons. 3. Axo-somatic synapse was not observed. The number of axo-dendritic synapse was 1.83$\pm$1.37 per labeled bouton. Majority(85.0%) of axo-dendritic synapses were formed with dendritic shafts, nonprimary dendrites(n=47, 1.57$\pm$1.38/1 bouton), however, synapses formed with primary dendrites(n=6, 0.20$\pm$0.41/1 bouton) or dendritic spines(n=2, 0.07$\pm$0.25/1 bouton) were rare. 4. 76.7%(n=23) of labeled boutons formed axo-axonic synapse (2.93$\pm$2.36/1 bouton) with p-endings containing pleomorphic vesicles. Synaptic triad, in which p-endings formed synapses with labeled boutons and dendrites adjacent to the labeled boutons simultaneoulsy, were also observed in 60.0%(n=18) of labeled boutons. From the above results, vibrissa afferent terminals of adult cat showed distinctive synaptic organization in the trigeminal interpolar nucleus, thus, suggests their correlation with the function of the trigeminal interpolaris nucleus, which participates in processing of complex sensory information such as two-point discrimination and motivational-affective action. Further studies on physiologic functions such as quantitative analysis on ultrastructures of afferent terminals and nerve transmitters participating in presynaptic inhibition are required.

• The Korean Journal of Zoology
• /
• v.34 no.3
• /
• pp.382-388
• /
• 1991

쥐의 교핵내에서 대뇌피질(또는 소뇌핵) 면면시 소뇌교핵계(또는 대뇌교핵계)의 연접구조의 변화에 대한 전자현미경적 관찰결과, 대뇌교핵계의 수입로 차단의 경우 소뇌교핵계의 신경섬유는 교핵세포의 원위 가지돌기쪽으로 발아하며, 소뇌핵 병변시 서뇌교핵계의 신경섬유는 근위가지돌기와 연접을 형성하거나 또는 여러개의 가지돌기 부속물들과 사구체형 연접복합체를 형성함이 밝혀졌다. 이상의 연구는 광학현미경적 관찰에서 언급된 대뇌피질(또는 소뇌핵) 병변에 따른 교핵내 신경종말의 밀도증가에 대한 보고를 뒷받침해주며, 소뇌핵 병변시 운동결핍증의 시간경과에 따른 회복에 대한 신경해부학적 근거를 제시한다.

• Animal Systematics, Evolution and Diversity
• /
• v.13 no.2
• /
• pp.93-102
• /
• 1997

Two new marine tardigrade species, Batillipes longispinosus n. sp. and B. orientalis n. sp. are described on the basis of the specimens collected from the intertidal or shallow sublittoral sands of South Korea. Both the present species are characteristic in the absence of any caudal appendage throughout their life span, and bearing the long clava or cephalic appendages with the long spinous process on the femur of legs IV. B. longispinosus n. sp. most resembles B. tuvernatis Pollock, but is easily distinguished from it by the flattened caudal region and prominently developed spine of legs IV. B. orientalis n. sp. is much related to B. roscoffensis Kristensen, in having the wing-formed lateral body prohection between legs III and legs IV, the papillae on the head region, and the smooth caudal region, but discernible from it in the general body shape and the relatively longer spine of legs IV.

• Journal of Life Science
• /
• v.21 no.1
• /
• pp.102-109
• /
• 2011

The genioglossus muscle plays an important role in maintaining upper airway patency during inspiration; if this muscle does not contract normally, breathing disorders occur due to closing of the upper airway. These occur because of disorders of synaptic input to the genioglossus motoneurons, however, little is known about it. In this study, the distribution of GABA-, glycine-, and glutamate-like immunoreactivity in axon terminals on dendrites of the rat genioglossus motoneurons, stained intracellularly with horseradish peroxidase (HRP), was examined by using postembedding immunogold histochemistry in serial ultrathin sections. The motoneurons were divided into four compartments: the soma, and primary (Pd), intermediate (Id), and distal dendrites (Dd). Quantitative analysis of 157, 188, 181, and 96 boutons synapsing on 3 soma, 14 Pd, 35 Id, and 28 Dd, respectively, was performed. 71.9% of the total number of studied boutons had immunoreactivity for at least one of the three amino acids. 32.8% of the total number of studied boutons were immunopositive for GABA and/or glycine and 39.1% for glutamate. Among the former, 14.2% showed glycine immunoreactivity only and 13.3% were immunoreactive to both glycine and GABA. The remainder (5.3%) showed immunoreactivity for GABA only. Most boutons immunoreactive to inhibitory amino acids contained a mixture of flattened, oval, and round synaptic vesicles. Most boutons immunoreactive to excitatory amino acids contained clear and spherical synaptic vesicles with a few dense-cored vesicles. When comparisons of the inhibitory and excitatory boutons were made between the soma and three dendritic segments, the proportion of the inhibitory to the excitatory boutons was high in the Dd (23.9% vs. 43.8%) but somewhat low in the soma (35.7% vs. 38.2%), Pd (34.6% vs. 37.8%) and Id (33.1% vs. 38.7%). The percentage of synaptic covering of the inhibitory synaptic boutons decreased in the order of soma, Pd, Id, and Dd, but this trend was not applicable to the excitatory boutons. The present study provides possible evidence that the spatial distribution patterns of inhibitory and excitatory synapses are different in the soma and dendritic tree of the rat genioglussus motoneurons.

• Journal of Life Science
• /
• v.19 no.8
• /
• pp.1062-1066
• /
• 2009

N-Acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) catalyzes the phosphorylation of GlcNAc to GlcNAc-6-phosphate (GlcNAc-6-P). Despite detailed characterization of the enzyme itself, there have been few studies on the expression of NAGK in mammalian tissues. In the rat hippocampal neuron in culture, NAGK-immunoreactivity (IR) formed clusters in somatodendritic domains. In this study we characterized the NAGK clusters that protrude out the long axis of dendritic shafts. By double-labeling of the neurons with antibodies against NAGK and various synaptic proteins, we show that NAGK is positioned at the base of spines, while there were no NAGK protrusions into inhibitory postsynaptic sites. Immunoblot analysis showed that NAGK was included in synaptosomes but not in PSD fractions. Our results indicate that the NAGK clusters at the dendritic periphery protrude into spines.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.3 no.1
• /
• pp.51-58
• /
• 1999

In this Paper, the Performance of the semi-anechoic chamber which is to be constructed by the cross-shaped ferrite absorbers with broadband frequency characteristics, has been evaluated by the image method. As a result it was confirmed that the cross-shaped absorber has excellent performance over the frequency range from 30 MHz to 3,000 MHz, while the tile and the gird-type ferrite absorbers have the bandwidth of 30 - 1,000 MHz.

• Applied Microscopy
• /
• v.30 no.3
• /
• pp.255-264
• /
• 2000

The topographic correlation between the processes of photoreceptor cells and nerve cells in the pineal organ of catfish, Parasiluns asotus, was studied using 3D electron microscopy. Upon examination, one neuronal cell process was found to pass through the intertwined processes of the photoreceptor cells. Interestingly , we observed two photoreceptor processes interlock, after which two buds from one process penetrated the other. Synaptic ribbons were observed in the cytoplasm of the photoreceptor cella, especially near the neuronal process. Macrophages were occasionally found to be contact with the outer segments of the photoreceptor cells in the pineal lumen.