• International Journal of Oral Biology
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• 제43권2호
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• pp.93-100
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• 2018

The investigation of the embryonic development of the cerebellum has a long history. The postnatal normal development of the cerebellum in rodents and other animals became a popular topic for morphological investigations nearly a century ago. However, surprisingly, only a few studies are available regarding the prenatal normal development of the rodent cerebellum, especially in guinea pigs. Cell proliferation is essential for the development of the nervous system. The assessment of cell proliferation can be achieved by using various methods. In this study, we investigated the cell proliferation of the cerebellar cortex in guinea pigs at different stages of pregnancy and in postnatal life. Fetuses were obtained by cesarean section at 50 or 60 days of gestation (dg). Immunohistochemistry was performed with proliferating cell nuclear antigen (PCNA) antibody in the cerebellum. Strong PCNA immunoreactivity was observed in the external granular layer (EGL), which is a neurogenic zone in the cerebellum. The proportion of PCNA-IR cells was greater at 1 week than at 60 dg in lobule I, but not lobule VIII. After 50 dg, the width of the EGL continued to decline until 1 week, due to the maturation of the EGL cells. These results demonstrate the pattern of PCNA immunoreactivity in the developing cerebellum of guinea pigs. This serves as a guideline to study abnormal cerebellum development.

• 대한수의학회지
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• 제39권3호
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• pp.628-634
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• 1999

We have studied, by a nonisotopic in situ end-labeling(ISEL) technique, frequency of apoptosis in the external granular layer(EGL) of the cerebellum of immature mice by ${\gamma}$-rays irradiation from $^{60}Co$ or diagnostic ultrasound exposure. The total number of normal cells and cells showing morphological features of apoptosis were counted. The frequency of apoptotic cells was expressed as a percentage of the total number of cells in EGL. The extent of changes following 200 cGy(1090 cGy/min) was studied at 2, 4, 6, 8, 12, or 24 hours after exposure. The maximal frequency was found 6~8 hours after exposure. The immature mice that received 18, 36, 54, 108, 198, 396 cGy of ${\gamma}$-rays or diagnostic ultrasound(7.5MHz, 4.2mW, $I_{SPTA}=7.9mW/cm^2$, $I_{SPTA}=114.3W/cm^2$) for 10 or 30 minutes were examined 6 hours after irradiation. Measurements performed after ${\gamma}$-ray irradiation showed a dose-related increase in apoptotic cells in each of the mice studied. The dose-response curves were analyzed by a linear-quadratic model ; frequency of apoptotic cell in the EGL was y = $(0.1349{\pm}0.01175)D$+$(-0.0001522{\pm}0.0000334)D^2$+0.048($r^2$ = 0.981, D = dose in cGy). In the experiment of ultrasound exposure, the frequency of apoptotic cell was $0.106{\pm}0.130$(10 minutes exposure) and $0.167{\pm}0.220$(30 minutes exposure). We estimated the relative dose of the yield from the experiment with ultrasound by substituting the yield from ultrasound exposure into the curve from the ${\gamma}$-irradiation. The relative dose of ultrasound exposure compared with ${\gamma}$-irradiation were 0.432 cGy(10 minutes exposure) and 0.885 cGy(30 minutes exposure). We have found that there is no evidence to indicate that diagnostic ultrasound involves a significant risk.

• 대한수의학회지
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• 제38권4호
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• pp.679-685
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• 1998

We have studied, by a nonisotopic in situ DNA end-labeling (ISEL) technique, frequency of apoptosis in the external granular layer (EGL) of the cerebellum after whole-body irradiation of newborn mice and intestinal crypt cell of adult mice by gamma-rays from $^{60}Co$. The extent of changes following 2 Gy(10.9 Gy/min) was studied at 2, 4, 6, 8, 12, or 24h after exposure. The maximal frequency was found 4-8h after exposure. The mice that received 0.18, 0.36, 0.54, 1.08, 1.98, or 3.96 Gy were examined 6h after irradiation. Measurements performed after irradiation showed a dose-related increase in apoptotic cells in each of the mice studied. The dose-response curves were analyzed by a linear-quadratic model; frequency(%) of apoptotic cell in the newborn mice cerebellum was ($13.49{\pm}1.175$)D+$(-1.52{\pm}0.334)D^2$+0.048($r^2=0.981$, D = dose in Gy) and frequency(number per crypt) of apoptotic cell in the intestinal crypt of adult mice was ($3.857{\pm}0.420$)D+$(-0.535{\pm}0.120)D^2$+0.155($r^2=0.952$, D = dose in Gy). It provides the basis required for a better understanding of results which will be obtained in any further studies for biological responses of radiation using newborn and adult mice.