The Effects of Hyperhomocysteinemia on the Ultrastructures of Cerebral Microvessels / 대한해부학회지

Elevated plasma level of the sulfur amino acid homocysteine, termed hyperhomocysteinemia, is now recognized as a contributing factor to various pathological states of the brain including vascular, degenerative and other neurologic disorders. Endothelial dysfunction may be one of the underlying mechanisms leading to proatherogenic and neurotoxic effects associated hyperhomocysteinemia. We conducted electron microscopic studies to investigate microvascular changes in hyperhomocysteinemic rat brain due to folate deficiency. Dietary folate deprivation caused an increase in plasma Hcy by 317% from 6.15 +/- 0.9 micro mol/l to 19.5 +/- 3.2 micro mol/l with time up to 8 weeks of folate deprivation. In electron microscopic study, perivascular amorphous fibrosis, and pericytic and endothelial cell degenerative appearance were frequently found in hyperhomocysteinemic microvasculature. These findings are very similar with the typical cerebral microvascular pathology observed in neurodegenerative and aging processes. From these results, it can be suggested that hyperhomocysteinemia -induced blood -brain barrier disruption give rise to subsequent neuronal dysfunction in hyperhomocysteinemia.

Morphological Changes of Astrocytes and Muller Cells in the Neonatal Rat Model of Retinopathy of Prematurity / 대한해부학회지

OBJECTIVES: Retinopathy of prematurity (ROP) is one of the major cause of vision loss among children. Recently, the prevalence of ROP is markedly increasing as the survival rate of very-low-birth-weight premature infants has been improved. It is widely accepted that retinal hypoxia results in the release of factors influencing new blood vessel growth. But, it is little known about the morphological changes of retinal astrocytes and Muller cells in the ROP model. So, we planned to investigate the morphological changes of those retinal glial cells induced by alternating hyperoxic and hypoxic injury in ROP. METHODS: Newborn rats (postnatal day 6) were exposed to two different oxygen concentrations alternating every 24 hours until postnatal day 14. Used oxygen concentrations were 10~15% for hypoxic episode and 55~80% for hyperoxic episode. Afterthen, they were returned to room air. A group of animal served as a room air control. Retinal vascularity was assessed by ADPase reaction and morphology of retinal glial cells was observed using transmisson electron microscope. RESULTS: Preretinal neovascular tufts were observed in 2 out of 12 animals of group III (75/10%) and 4 out of 12 animals of group IV (80/10%), respectively. There was no remarkable structural change of astrocytes. But we could observe some morphological changes of Muller cells. Retraction of the radial processes of Muller cells and breaking of basal lamina were noted at the site of preretinal neovascularization. Decrease in the space occupied by the cytoplasmic processes of Muller cells was observed in the inner nuclear layer of group IV retinae. Infiltration of microglia or macrophage into the vitreo-retinal interface and the site of extravasation was noted. Findings suggestive of neuronal cell death were also observed especially in the inner nuclear layer. CONCLUSIONS: Morphological change of Muller cells and resultant loss of integrity of internal limiting membrane seemed to be the most important step for preretinal neovascularization. But, no structural changes of astrocytes were noted.

Migration of Normal Corneal Epithelial Cells in Rats / 대한해부학회지

In the stratified squamous epithelium, most of basal cells in the entire epithelium function as stem cells. But many researchers report that stem cells in the corneal epithelium are located exclusively in the limbus. We planned to investigate the morphological characteristics of migrating corneal epithelial cells by the electron microscopy. Sprague-Dawley rats at fullterm, postnatal day 5, 10, 15, and adult were used as experimental animals. The results are as follows. 1. Stratification of the corneal epithelium : The number of layers in the corneal epithelium was dramatically increased in the period between postnatal day 10 and 15. 2. Migration of the corneal epithelial cells : In the groups of postnatal day 10 and adult, wide intercellular spaces were noted. Especially in the adult, the limbal side of basal cells was being lifted from the Bowman's membrane and centripetal polarity of them are noted. According to the above results, the wide intercellular spaces at postnatal day 10 seems to be resulted from the migration of corneal epithelial cells for epithelial stratification. The centripetal polarity of limbal basal cells in adult rat suggests that only the limbal basal cells may function as stem cells in that period.

Synaptic Morphology of the Mouse Striatal Cholinergic Neurons in the Early Postnatal Life / 대한해부학회지

The cholinergic neurons in the striatal complex are the major interneurons that integrate the informations incoming to and outflowing from the striatum. The shape of synapses may change even after birth and the synaptic morphology reflects the functional state of synapse. However, it is not well known about the synaptic morphology of the mouse striatal cholinergic neurons in their early postnatal life. Thus, we investigated the synaptic morphology of the mouse striatal cholinergic neurons in their early postnatal life by the electron microscopy combined with immunohis-tochemistry. In addition, we investigated the trends of change in synaptic morphology and whether the difference between two compartments exists or not. Experimental animals which are ICR mice, were divided into 5 groups according to their postnatal age: 3-day, 1-week, 2-week, 4-week, and 6-week. Pre-embedding immunohisto-chemistry was done with anti-choline acetyl transferase antibody. The results were as follows. 1. In synapses that immunoreactive terminals constitute the presynaptic components, most of synapses are symmetric type in all age groups (p<0.05). Most of synapses in the dorsal striatum are symmetric form from 1-week of postnatal age, but it is not prominent in the ventral striatum until 2-week of postnatal age. 2. In synapses that immunoreactive terminals constitute the postsynaptic components, both symmetric and asymmetric synapses are noted in similar proportions (p<0.05). There are no difference in the synaptic morphology between dorsal and ventral striatum. 3. No specific findings are observed in synaptic curve according to the postnatal age or compartment. In conclusion, the synaptic morphology of mouse striatal cholinergic neurons is similar to mature pattern from 2-week of postnatal age. And it is thought that period between birth and 2-week of postnatal age is the critical period for synaptogenesis. The synaptic curve does not reflect the degree of synaptic maturity. Further investigations will be required to generalize the synaptic curve as a marker for synaptic maturity.

Human genomic DNA isolation and chromosomal localization of fetal brain cDNA (FB174) / 대한해부학회지

Eventhough surmountable amounts of genes are being cloned and a number of methods are being developed by human genome project, it's not easy to predict possible functions of genes and determine the chromosomal locations of genes. In this experiment, cDNA pool was made from 18 weeks old human fetal brain and analyzed the sequences. FB174 clone was chosen, in situ hybridization histochemistry was performed on developing and adult rat tissue section to observe the tissue specificity and developmental expression of this gene. To observe the chromosomal location of FB174 clone, the genomic DNA from human genomic library was isolated and fluorescence in situ hybridization was carried out. By sequencing and sequence search with GenBank data it was revealed that cloned FB174 cDNA was quite similar to translationally controlled tumor protein which is known to locate to human chromosome 13q14. The expression of FB174 mRNA was not detected in rat tissue sections by in situ hybridization histochemistry. Fluorescence in situ hybridization using biotin labeled FB174 probe resulted in specific labeling of human chromosome 7q22. These results and high sequence homology of FB174 to known translationally controlled tumor protein suggest that FB174 clone may be a new translationally controlled tumor protein-related gene.

Distribution of the Mouse Striatal Cholinergic Neurons in Their Early Postnatal Period / 대한해부학회지

The category of striatal complex contains caudate nucleus, putamen, nucleus accumbens septi, and olfactory tubercle. The striatal complex is composed of two compartments, dorsal and ventral striatum. In the striatum, cholinergic neuron is known as one of the most important intrinsic neurons, but there were little morphological reports about the early postnatal expression of mouse striatal cholinergic neurons. So, we planned to investigate the distribution of mouse striatal cholinergic neurons in their early postnatal period by the immunohistochemistry. We used ICR mouse as the experimental animals and divided them into 5 groups according to their postnatal age : 3-day, 1-week, 2-week, 4-week, and 6-week. Immunohistochemistry was done with anti-choline acetyl transferase antibody (chemicon). The results were as follow. 1 The striatal cholinergic neurons are already detected in the 3-day group, but the intensity was weak and the expression rate was extremely low. In the caudoputamen, the cholinergic expression rate was increased significantly between 3-day and 2-week. And in the nucleus accumbens septi, it was increased significantly between 1-week and 2-week. 2. The cholinergic expression rates of the adult mouse striatum were similar in both compartments. But, the difference of maturational time was noted. In the dorsal striatum, the cholinergic expression rate was increased significantly in the first postnatal week, but in the ventral striatum, it was approached to the adult level only after second postnatal week. In conclusion, the cholinergic expression rate in the mouse striatum was significantly increased after birth. And it was approached nearly to the adult level after 2-week of postnatal age. But, according to the compartments or rostrocaudal subdivisions, the difference of maturational time was noted.

In vitro Immunization of Human Tonsilar Lymphocytes Using Slice Culture Sytem / 체질인류학회지

It is difficult to immunize human lymphocytes in vitro by conventional cell culture methods. Activation of lymphocytes requires not only specific antigen stimulation but also delicate cell to cell interaction. If the cellular organization could be maintained in culture system, lymphocytes could be immunized in vitro with higher frequency. For the purpose of in vitro immunization of human lymphocytes, we used slice culture system which could maintain morphological and functional organization. Human tonsils resected from eleven -year old boy were evenly divided into two pieces, and one was cultivated in conventional cell culture and the other in slice culture system. In the former system, tonsilar mononuclear cells, separated by Ficoll -Hypaque density gradient centrifugation, were cultivated in RPMI 1640 supplemented with 10% human type AB serum in the cell density of 5 x10 6 /ml. In the latter, tonsillar tissues were sliced into small pieces of 8 mm 3 , and were cultivated in Waymouth MB 752/1 medium supplemented with 10% Human type AB serum, gassed under 5% CO2 and 95% O2 at 37 C. After stabilized for one hour, each system wasw challenged with 50 microgram/ml of KLH or 100 microgram/ml of LPS. At 3, 6, 12 and 24 hours after antigen challenge, culture supernatants were assayed for the specific antibody by ELISA, and cells or tissues were analyzed for the expression of CD23 by flow cytometry. The result showed that tonsilar B lymphocytes in slice culture system expressed CD23 as early as 3 hours after antigen challenge, while those in cell culture system expressed CD23 from 6 hours after challenge. Specific antibodies were detected only in supernatants of slice culture system from 6 hours after challenge. These results suggested thathuman lymphocytes could be immunized in vitro if the cellular organization was maintained.

Ultrastructural localization of serotonin 2 receptor sites in the synapses of rat hippocampus by means of 3H-ketanserin binding / 대한해부학회지

No abstract available.

Morphometric study on the synapses in the neostriatum of the rat after exposure to alcoholll during fetal and lactating period / 대한해부학회지

No abstract available.