• Applied Microscopy
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• 제18권2호
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• pp.177-186
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• 1988

Degeneration of the axon terminals of mamillo-thalamic tract following the electrical coagulation of mamillary body is well known. In this study, the author investigated the ultrastructural alterations of neuropil components, initiated by terminal degenerations. Rats weighing approximately 250 gm were fixed on the stereotaxic instrument(David Kopf Inc., Heavy duty model), and NE 300 active electrode(Rhodes Med. Instr. Inc.) was introduced to the mamillary position of anterior 3.8 mm, lateral 0.5 mm, height 3.8 mm and lateral angle of $23^{\circ}$ according to De Groot's Atlas. Electric current of 20 mA was applied during 1 minute between active and inactive electrodes with Radio Frequency Lesion Generator(RFG 4, Radionics Inc.). Two hours, 2 days, 1 week and 2 weeks following the electrical coagulation of mamillary body, ipsilateral anterior thalamic nucleus was fixed in 1% glutaraldehyde-l% paraformaldehyde and 2% osmium tetroxide, embedded in Araldite mixture, cutted with LKB ultra tome V, stained with uranyl acetate-lead citrate and observed with JEOL 100 CX electron microscope. Observed results were as follows; 1. Degenerated mamillo-thalamic synapses were observed to form asymmetric axospinous or axo-dendritic types. 2. Terminal degeneration was not easily discernible at 2 hours interval after mamillary lesion, but following 2 days the terminal degeneration was apparent. 3. Postsynaptic spines, dendrites and even their cell bodies show edematic changes caused by the degeneration of postsynaptic counterpart. 4. Astrocytic territories, including perivascular processes forming glial limitans of blood-brain barrier, exhibit remarkable expansion. 5. Oligoglia and astroglia are actively engaged in the removal of degenerated elements. 6. Active forms of microglia were increased. 7. The observed results may represent typical ultrastructural alteration pattern within neuropil following the degeneration of certain input axon terminals.

• Journal of Korean Neurosurgical Society
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• 제29권5호
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• pp.599-603
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• 2000

Objectives : In lumbar spine surgery it is observed that the ligamentum flavum(LF) is bilayered, and the inner layers can be left in situ to prevent peridural adhesion in open lumbar disc surgeries. The purposes of this study are to investigate ultrastructural differences between the inner and outer layer of lumbar LF by electron microscopic examination, and to see whether these differences are, if present, more prominent in chronic degenerative lumbar spinal disorders as compared with acute lumbar disc diseases. Methods : Biopsy specimens of LF were obtained from nine patients undergoing lumbar spine surgery, five of them for degenerative spinal stenosis and four for acute disc herniation. During the surgery the outer layers of LF were carefully dissected from the inner layer, and four pieces($1{\times}1{\times}1-mm$) of biopsy samples were made from each layer. These were examined with electron microscope for the morphologies and the contents of the elastic and the collagen fibers. Results : The outer layer of LF showed elastic fiber degeneration as evidenced and decreased fiber content, while the inner layer was relatively preserved in both cases of degenerative spinal stenosis and acute disc herniation. The ultrastructural changes of the layers were more evident in the outer layer. Conclusion : With these observations the authors believe that the LF degeneration may occur mainly in the outer layer, and that this fact may aid in making the rationale for using the inner layer as physiologic barrier to prevent peridural adhesion in open lumbar disc surgeries.

• Toxicological Research
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• 제35권3호
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• pp.257-270
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• 2019

Silver nanoparticles (AgNPs) have been widely used in a variety of applications in innovative development; consequently, people are more exposed to this particle. Growing concern about toxicity from AgNP exposure has attracted greater attention, while questions about nanosilver-responsive genes and consequences for human health remain unanswered. By considering early detection and prevention of nanotoxicology at the genetic level, this study aimed to identify 1) changes in gene expression levels that could be potential indicators for AgNP toxicity and 2) morphological phenotypes correlating to toxicity of HepG2 cells. To detect possible nanosilver-responsive genes in xenogenic targeted organs, a comprehensive systematic literature review of changes in gene expression in HepG2 cells after AgNP exposure and in silico method, connection up- and down-regulation expression analysis of microarrays (CU-DREAM), were performed. In addition, cells were extracted and processed for transmission electron microscopy to examine ultrastructural alterations. From the Gene Expression Omnibus (GEO) Series database, we selected genes that were up- and down-regulated in AgNPs, but not up- and down-regulated in silver ion exposed cells, as nanosilver-responsive genes. HepG2 cells in the AgNP-treated group showed distinct ultrastructural alterations. Our results suggested potential representative gene data after AgNPs exposure provide insight into assessment and prediction of toxicity from nanosilver exposure.

• Applied Microscopy
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• 제16권2호
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• pp.75-91
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• 1986

Differentiation of the rat testis was studied by light and electron microscope from the fetal stage up to the newborn or adult stage. The purpose of the present study is to investigate the ultrastructural changes of seminiferous tubules and interstitial tissue during the developmental process. The results were as follows: the seminiferous tubule diameter began to increase from birth and was fully developed at 30 to 40 days of age through intratubular cell proliferations. Basement membrane and myoid cells lining the seminiferous tubules were differentiated at 17 days gestation. At the fetal stage, seminiferous tubules were primarily composed of Sertoli cells and the differentiation of Sertoli and germ cells progressed from the newborn stage. Spermatids and immature spermatozoa are appeared at 40 days of age, so from this time, spermatogenesis occurred actively until the adult stage. Sertoli cells aided germ cell differentiation and phagocytosed the parts of the spermatid cytoplasm. Leydig ce]] development follows a biphasic pattern: a fetal phase and then an adult phase from 20 days of age. In conclusion, the rat testis is already developed to some extent by the fetal stage and is functional after 50 days of age. Therefore, these findings indicate that differentiation of Sertoli and Leydig cells precedes the onset of spermatogenesis.

• 한국패류학회지
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• 제26권1호
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• pp.79-84
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• 2010

A morphological and ultrastructural study on the prostate of a land snail Nesiohelix samarangae was conducted. The prostate of Nesiohelix samarangae is a tubular gland connected with the large hermaphrodite duct. The lining of the prostate tubules possesses two distinct types of epithelial cells, one secretory and the other non-secretory. The secretory cells contained numerous secretory granules in various sizes and electron density. Most of the secretory granules showed light electron density but some of them showed heavy density. The ciliated cells were non-secreting cells situated only toward the lumen of the tubules and appeared as ordinary epithelial lining cells. The ciliated cells of the epithelium extensively interdigitate with each other and their apical surfaces had numerous cilia and microvilli. The bases of the ciliated cells did not reach the basal region of the secretory cells.

• 한국패류학회지
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• 제14권2호
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• pp.131-147
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• 1998

A histochemical and ultrastructural study on the epithelia of some selected digestive tracks such as esophagus, crop, intestine of a land snail N. samarangae was carried out during the period of June 1997 to may 1998. The epithelium of digestive tract are simple columnar epithelium and consisted of five types of columnar cells. Type 1 cell which is majority in number has a brush border with microvilli on the free surface of the cell and contains numerous secretory granules supposed to be neutral mucopolysaccharide. Type 2 cell, elongated conical in shape, is rarely found in the epithelium. This cell also has a brush border with microvilli on its free surface and contains well developed rough surfaced endoplasmic reticulum, Golgi bodies, and secretory granules in various electron densities. This cell seems to produce both of acid and neutral mucopolysaccharides. Type 3 cell, which is morphologically similar to the Type 1 cell, has microvilli and cilia on the free surface and exists in group only in the limited regions of the intestine. Type 4 cell, typical goblet cell containing secretory granules in high electron density. Type 5 cell rarely found in the digestive tract. This cell contain inconspicuous materials.

• Applied Microscopy
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• 제42권4호
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• pp.179-185
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• 2012

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. Neuropathological hallmarks of AD are amyloid plaques, dystrophic neurite, and alteration of subcellular organelles. However, the morpho-functional study of this degenerative process and ultimate neuronal death remains poorly elucidated. In this study, immunohistochemical and ultrastructural analyses were performed to clarify the abnormal morphological alterations caused by the progression of AD in APP/PSEN1 transgenic mice, express human amyloid precursor protein, as a model for AD. In transgenic AD mice brain, the accumulation of Amyloid ${\beta}$ plaques and well-developed dystrophic neurites containing anti-LC3 antibody-positive autophagosomes were detected in the hippocampus and cortex regions. We also found severe disruption of mitochondrial cristae using high-voltage electron microscopy and three-dimensional electron tomography (3D tomography). These results provide morpho-functional evidence on the alteration of subcellular organelles in AD and may help in the investigation of the pathogenesis of AD.

• 한국축산식품학회지
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• 제32권5호
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• pp.578-583
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• 2012

The purpose of this study was to evaluate the ultrastructural and shear force changes of duck breast and leg meat during aging at $0^{\circ}C$. Pekin ducks (45 d old) purchased from Greemud Co. were used for this experiment, and were stored at $0^{\circ}C$ for 7 d in order to determine the changes of the meat structure using transmission electron microscopy (TEM) and shear force. At day 0, A-band, I-band, M-line and Z-line of sarcomeres were seen clearly, but sarcomeres started to lose structure and become extended in length from day 2. With extended aging periods, myofibrils were destroyed and symptoms of aging became more obvious. In the duck breast meat, some myofibrils were also destroyed at the Z-line, but were mainly destroyed at the M-line. The change in structure of duck leg meat over time was similar to that of breast meat. After five days and seven days of aging, mitochondria size and quantity were determined to be increased between the myofibrils. Shear force was decreased over time. From this study, aging at $0^{\circ}C$ was found to negatively influence the ultrastructure and shear force of duck meat.

• Applied Microscopy
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• 제46권2호
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• pp.83-88
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• 2016

Structural differentiation of the connective stalk in giant duckweed, Spirodela polyrhiza, was examined to reveal the anatomical and ultrastructural characteristics within reduced shoot. The study focuses primarily on structural features of the connective stalk (CT), which connect offspring to their mother fronds. Photoautotrophic offspring fronds remained connected by stalks to mother fronds in the reproductive pockets until separation. The CT originated from the meristematic region of the abaxial frond and joined the fronds laterally with two abscission layers. The most notable features of the CT were polymorphic mitochondria, random occurrences of fibrillar structures in intercellular spaces, and great variability in cell wall thickness. Vascular tissues in CTs were highly reduced, demonstrating only a central vascular strand. Grana with 2 to 4 thylakoids and starch grains were found in the chloroplasts. A chlorophyll assay indicated high chlorophyll concentrations in daughter fronds and low concentrations in CTs. The frond and CT, while physically connected to each other, functioned independently. Despite great reduction in S. polyrhiza, the CT has proven to be very efficient for separating offspring from the mother frond, which lends to its capacity for rapid vegetative reproduction. The ultrastructural aspects of CTs in S. polyrhiza were characterized for the first time in this study.

• 생명과학회지
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• 제19권8호
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• pp.1016-1022
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• 2009

융단조직은 약실 내에서 발달하는 소포자에 영양분을 공급하고 퇴화되는 조직으로써, 소포자 4분자 시기에 최대로 발달하고 화분벽에 포분질에 축적된 후 프로그램 세포사가 일어남으로써 세포가 죽게 되고 융단조직 전체가 퇴화된다. 액포가 융합되므로써 프로그램 세포사가 시작되고 세포질응축, 핵질 분절 등이 뒤따라 일어난다. 지질 덩어리는 비교적 늦은 시기에 퇴화되며 orbicular body는 가장 늦게까지 남아 있게 된다. 융단세포의 프로그램세포사 전 과정 중에서 세포벽은 액포에서 기원하는 가수분해 효소에 비교적 안정적이므로 가장 늦게 퇴화되는 것으로 확인되었다.