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KMID : 0364219840270010013
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Korean Journal of Zoology
1984 Volume.27 No. 1 p.13 ~ p.24
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UV Effect on the Number of Primordial Germ Cells in the Embryo of Rana dybowskii
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Chung Hae-Moon
Kim Won-Sook
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Abstract
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The fertilized eggs of Rana dybowskii were irradiated with UV (254 nm wave length) on the vegetal hemisphere to investigate the effects on the primordial germ cells (PGCs) and axis formation. The investigations were carried out in two ways; namely time course and UV dose. Up to 1,600 $ergs/mm^2$ of UV dose, irradiated at 60 min. after fertilization, there was no effect on the PGC number. However, the number of PGC comparing with that of unirradiated control was decreased more than 40%. As the amount of irradiation was increased, the number of PGC was inversely declined. The maximal dose of irradiation which eliminates PGC completely without inducing any axis abnormality was 4,800 $ergs/mm^2$. If the eggs were irradiated earlier with this amount the severer effect could be obtained. Thus the UV effect on the PGC number was most effective when irradiated by 60 min. post fertilization. Thereasfter stage. At UV doses over 9,600 $erge/mm^2$ other effects start to appear; namely abnormalities of nerual tube and axis formation. Therefore, comparative study on the UV sensitivity of PGC and axis formation was carried out. It was revealed that UV effect on the axis was drastically decreased at the time of $0.7\\sim0.8$ between fertilization and 1st cleavage, while the germ plasm was sensitive to UV until 4 cell stage.
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