• Applied Microscopy
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• v.21 no.2
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• pp.96-116
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• 1991

The authors studied the morphological distinctions of each of the epidermal layers and the time of appearance of the keratohyalin granules and tonofilaments by the processing of development. The skins were obtained from fetal rats at the age of 14th, 16th, 17th, 18th, 19th and 20th day of gestation, of 1st and 3rd day of neonatal life and of 4th week after birth. The specimens were staind with uranyl acetate and lead citrate. The results obtained were as follows. 1. On the 16th-gestation day, the intermediate layer which contained numerous ${\alpha}-and\;{\beta}$-glycogen particles was appeared, and hemidesmosomes and desmosome were observed as well. 2. Tonofilaments were first observed on the 17th gestation day. 3. Above-mentioned intermediate layer was differentiated into the granular layer and the spinous layer on the 18th-gestation day. Keratohyaline granules were appeared in association with the ribosomes and the tonofilaments and the compound granules were lipoid granules which were surrounded by ribosomes at the periphery. 4. Ultimately, keratinization began to take place from the 20th-gestation day. At the age of 4th week, the thickeness of epidermis and the amount of keratohyaline granule and tonofibrils were decreased. It is consequently suggested that in the differentiation process of the rat epidermis, keratinization begins after formation of hemidesmosomes and desmosomes, from which the tonofilaments are formed and after keratohyaline granules are formed. Therefore appearance of the keratohyaline granules and formation of the tonofilament appears to have a close relations with the keratinization process of the rat epidermis.

• Korean Journal of Veterinary Research
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• v.52 no.3
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• pp.199-203
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• 2012

Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the development of nerve fibers in the rat sciatic nerve, the initial development of NF155 in the paranode was studied with immuno-fluorescence and immuno-electron microscopy. The result of the present study showed NF155 was not detected in the fetal sciatic nerve and began to reveal at the postnatal day 0 (P0) and dramatically increased by time lapse until postnatal day 7 (P7). NF155 was prominently localized in the axolemma of paranode and not detected in the central region of node of Ranvier. According to the present study, NF155 is likely to have some relationships with the formation of paranode and myelin sheath.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.769-786
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• 1998

The purpose of the present study is to examine the effect of cell proliferation and alkaline phosphatase activity in osteoblastic cells and to compare the bone healing ability of rat calvarial defects between the control group and the safflower seed extract treated group. Osteoblastic cells were obtained from calvariae of a fetal rat. Cells were cultured containing DMEM and safflower seed extract ($10^{-6}g/ml$, $10^{-3}g/ml$) at $37^{\circ}$ with 5% $CO_2$ in 100% humidity for 3 days. MTT was performed to examine the viability of the cells, and alkaline phosphatase activity was analyzed to examine the mineralization in vitro. Rat calvarial defects($5{\times}5mm$) in 250g Sprague-Dawly were made using round bur. Rats were administrated with safflower seed extract(0.35g/kg/day) for experimental periods. Calvarial defects were studied histopathologically and immunohistochemically at 1,4, and 8 weeks. High concentration group($10^{-3}g/ml$) of safflower seed extract significantly increased in the cell proliferation and alkaline phos phatase synthesis in osteoblastic cells. The infiltration of inflammatory cells and osteoclastic activities were decreased in the safflower seed extract treated group as compared with control group. Bone maturation was accelerated in the safflower seed extract treated group as compared to control group. No difference in osteoinductive process was observed between the control and the safflower seed extract treated group. Immunohistochemical observation revealed that protein expression of TGF-$\beta$and osteonectin during early healing phase in the safflower seed extract treated group was slightly increased as compared to control group. These results indicate that safflower seed extract promotes the healing process in bony defect of rat calvariae, and retains a potential applicability as an adjuvant therapeutic modality for regeneration of periodontal bony defect.

• Development and Reproduction
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• v.4 no.1
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• pp.95-100
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• 2000

A large number of man-made chemicals that have been released into the environment have the potential to disrupt the endocrine system of animals and humans. There is a critical developmental period during which sexual brain differentiation proceeds irreversibly under the influence of gonadal hormone. Recently we identified KAP3 gene expressed during the critical period of rat brain sexual differentiation. KAP3 functions as a microtubule-based motor that transports membranous organelles anterogradely in cells, including neurons. In the present study, we aimed to investigate the effect of endocrine disrupter, Dichlorodiphenyl trichloroethane (DDT), on the KAP3 gene expression during critical period of rat brain development. Maternal exposure to DDT increased the level of KAP3 mRNA in male and female fetus brains when examined on the gestational day 17 (GDl7). In postnatal day 6, DDT suppressed the expression of KAP3 gene in male and female rat brain. Also, the body weight and fertilization rate were decreased in the DDT exposured rats. These results showed that endocrine disrupter, DDT, can affect the transcriptional level of brain sexual differentiation related gene, KAP3, in the prenatal and the neonatal rat brain and that maternal exposure to endocrine disruptors may lead to a toxic response in embryonic differentiation of brain. And so KAP3 gene may be used a gene maker to analyse the molecular mechanism for toxic response in animal nerve tissues exposed to endocrine disruptors.

• Applied Microscopy
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• v.23 no.1
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• pp.56-76
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• 1993

To investigate the histogenesis of tracheal epithelium in Sprague-Dawley strain rat, the author has used the fetal rats at the 16th, 18th, 20th and 22nd prenatal day and neonatal rats at the 1st and 7th day as well as rats at age of 5, 10 and 15 weeks after birth as experimental animals. Specimens were double stained with uranyl acetate and lead citrate for electron microscopic study. The results obtained were as follows; 1. At the 16th day of gestational age, ciliated cells were found in tracheal epithelium and light and dark ciliated cells possessing numerous mitochondria and smooth endoplasmic reticulum in the cytoplasm at the 22nd day of gestational age of the rat are observed. 2. At the 16th day of gestataional age, basal cells lying upon the basement membrane and having large numbers of glycogen particles in the cytoplasm, were found and at the 22nd day of gestational age, basal cells possessing numerous polysomes in the cytoplasm were observed. 3. At the 20th gestational age of the rat, microvillous cells possessing many rough endoplasmic reticulum and mitochondria as well as microvilli protruding into the lumen were found in tracheal epithelium. 4. At the 5th week after birth brush cell having profound filamentous strands and many pinocytic vesicles in the cytoplasm, was visible in the tracheal epithelium. 5. At the 15th week after birth large proportions of tracheal epithelium were lined with ciliated cells. Cosequently it is suggested that pseudostratified ciliated columnar epithelium was differentiated at the 16th day of gestational age, in addition cytoplasmic organelles of the microvillous and basal cells were matured at the 20th and 22nd gestational age, respectively and most of the part of the tracheal epithelium was lined with ciliated cells at the 15th week after birth.

• Journal of Periodontal and Implant Science
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• v.29 no.4
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• pp.765-785
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• 1999

Bone morphogenetic protein-2/4 (BMP-2/4) are members of Transforming Growth $Factor-{\beta}\;(TGF-{\beta})$ superfamily and they may differentiate the osteoprogenitor cell and induce formation of cartilage and bone in vivo. This study was performed to investigate the effects of bone morphogenetic protein-2/4 on the characteristics of rat periodontal ligament cells(RPDL) and rat calvaria cells(RCV). In the control group, the cells were cultured alone with Dulbeco's Modified Eagle's Medium contained with 20% fetal bovine serum, $100{\mu}/ml$ penicillin, $100{\mu}/ml$ streptomycin. In the experimental groups, recombinant human bone morphogenetic protein-2/4 (25ng, 100ng, 250ng/ml) were added into the above culture condition. And then each group was characterized by examing the cell proliferation at 1, 2, 3, 5, 7th day, the amount of total protein synthesis and alkaline phosphatase activity at 2, 5, 7th day. And also, the calcified nodule was examed. The results were as follows ; 1 . Both RCV and RPDL cells in both control and experimental groups proliferated during the entire experimental period, but there is no stastically significant difference according to the BMP-2/4 concentration. 2 . Amount of total protein synthesis of both cells in both groups was steadily increased until 5th day, but all experimental groups were significantly different from the control group at 7th day. 3. Alkaline phosphatase activity of both cells in both groups was increased during the entire experiment period. In RCV cells, the experimental group treated with 100ng/ml and 250ng/ml BMP-2/4 were significantly different from the control group at 7th day. In RPDL cells, the experimental group treated with 100ng/ml and 250ng/ml BMP-2/4 were significantly different from the control group at 5th day, and all experimental groups were significantly different from the control group at 7th day. 4. In the both of the cultured Rat Periodontal ligament and calvaria cell treated with BMP-2/4 to compared with control group, it revealed more rapid cell polarization, cell aggregation and hyperchromatic stained on HE agent, and even though only 1 day treated with BMP-2/4 both RPDL and RCV showed more rapid cell reaction than control group. More sensivitve cell reaction of RCV were observed than RPDL in this experiment. From the above results, we could conclude that BMP-2/4 influenced the induction, proliferation and differentiation of bone forming cells

• Journal of Life Science
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• v.17 no.10
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• pp.1347-1353
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• 2007

The changes of glycoconjuagates (GCs) in rat kidney due to maturation were studied from samples of fetal and postnatal kidneys by lectin histochemistry. Rat kidneys of perinatal ages and adults were fixed in 4% paraformaldehyde and were stained with nine kinds of biotinylated lectins. The immature forms of the renal developmental stage such as vesicles and ureteric bud were observed in the cortex as late as day 14 of postnatal life, but the histological appearance of the weaning kidney was similar to that observed in adults. As for histochemical properties of GCs in the glomeruli, Con A affinity tended to increase with aging, but both RCA-1 and LCA affinities showed a transient increase in immature glomeruli of neonatal rats. DBA affinity with SBA, PNA, BSL-1 and RCA-1, additional Con A one in proximal tubule, were increased in both proximal and distal tubules according to maturation. In contrast to this, transient intensive LCA affinity were demonstrated in immature proximal and distal tubule of neonatal rats. In the collecting tubules, DBA, SBA, PNA and sWGA affinities tended to increase according to maturation, but transient increase for BSL-1, RCA-1 and LCA affinities were detected in neonatal rats. The present results suggest that the mature glycosylation pattern of the kidney undergoes profound changes during maturation and is probably associated with functional maturation of the kidney.

• Applied Microscopy
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• v.34 no.2
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• pp.145-157
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• 2004

The aim of the present study was to examine in detail, both at light and electron microscopical levels, the morphological variations in ameloblast of the fetal rat incisor enamel organ. Rats were started on distilled water at the beginning of pregnancy. The pups were sacrificed 11 days after delivery and animals were perfused intravascularly with glutaraldehyde and the incisors were removed. To examine on the ultrastructure of the ameloblast, the study employed primary light microscopy but electron microscopy was used to clarify some of the light microscopic finding. Longitudinal sections through the incisors of the rat show a continuous layer of ameloblasts on the labial surface of the tooth. This layer contains the entire sequence of developmental stages in enamel production. The ameloblast layer was divided into three main zones: 1) Presecretory zone, region of ameloblasts facing pulp. 2) Secretory zone, region of inner and outer enamel secretion. 3) Maturation zone, region of reduced ameloblasts. In particularly, the present study has shown that two distinctively different types of ameloblasts appear in the enamel organ during enamel maturation in the rat incisor. These two types have been designated ruffle-ended ameloblasts (rAB) and smooth-ended ameloblasts (sAB). The fluoride produces marked alteration in the fine structure of ameloblast from teeth of young rats, such as large confluent distensions of the endoplasmic reticulum and swelling of isolated mitochondria. This experimental data suggested that exposure prolonged of animal to high level of fluoride appears to induce a few dramatic changes in the normal appositional growth and initial mineralization of enamel created during amelogenesis.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1206-1212
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• 2000

This study was conducted to know whether Gamiyookmijihwangtang(GY) which is Yookmijihwang added with Liriopis tuber, Anemarrhenae rhizoma and Phellodendri cortex can remedy the overt diabetes in diabetes-prone BB(BBDP) rats. The rats were given GY through the mother from the fetal stage until birth. After birth they received GY through breast feeding until 20 days old. From 21 days old which is the beginning of the weaning period 60 BB rats(30 males and 30 females) were divided into 2 experimental groups(BBDP and BBDP-GY) and placed individually in metabolic cages. BBDP was the control group which didn't receive any GY and BBDP-GY received 16 mL/㎏ B.W./day of GY until 120 days old. The antidiabetic effects of GY were characterized by the clinical features such as polyurea, polydipsia, hyperglycaemia and the rapid loss of body weight. Body weight, water consumption, urine volume and blood glucose level showed no signs of impending diabetes but after onset there were big changes in those parameters. The onset of diabetes was delayed and the incidence of diabetes was also much decreased with GY but after onset there were no beneficial effects from it.

• The Korean Journal of Pharmacology
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• v.26 no.1
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• pp.1-6
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• 1990

We established an in vitro system of central serotonergic neurons by culturing dissociated rat embryonic (El4) brainstem cells to 14 days in vitro and monitored the serotonergic neuronal growth by measuring 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents in the cells with hish performance liquid chromatography with electrochemical detection (HPLC-EC). We studied also tile effects of various drugs on the contents of 5-HT and 5-HIAA, confirming in vivo reports. The 5-HT content (13 ng/mg protein) and 5-HT turnover rate (17 pmol/mg protein/h) at 14 days in vitro were in good agreement with those reported in the adult rat brain. The 5-HT content was more easily depleted with p-chlorophenylalanine, a tryptophan hydroxylase inhibitor than with NSD 1015 (3-hydroxybenzylhydrazine), an aromatic L-amino acid decarboxylase (AADC) inhibitor. Incubation of the cultures with tryptophan or 5-hydroxytryptophan increased the rate of serotonin formation implying that neither tryptophan hydroxylase nor AADC is saturated with its amino acid substrate in this in vitro system . The 5-HT content was depleted by reserpine. The 5-HT and 5-HIAA contents were increased and decreased, respectively, by monoamine oxidase inhibitors. All the above results indicate that the biochemical properties of the central serotonergic neurons in this culture system reflect reliably those of central serotonergic neurons in vivo. We suggest that measuring 5-HT and 5-HIAA contents in the primary cultured dissociated brainstem-cells with HPLC-EC is useful in the study of pharmacology as well as toxicolgy of the central serotonergic neurons.