Abstract
The present study was undertaken to examine the DNA synthesis activity in the first lower molar tooth germs of neo-natal rat cultured under a low-calcium environment. The right and left first lower molar tooth germs were extracted from 12 neo-natal Wistar rats. The right and left molar tooth germs were used as control and low Ca groups respectively. (3H) thymidine (1μCi/ml) was added to the cultures medium at day 8 in culture and the cultures were incubated for another 24 and 48 hours respectively, and the incorporation of [3H] thymidine into the tooth germs was examined.
The amount of incorporation of [3H] thymidine into tooth germ decreased with time in both control and low Ca groups. The degree of the decrease was higher in the control group than in the low Ca group. The amount of incorporation of [3H] thymidine was more in the low Ca group than in the control group in both 24-and 48- hour-culture periods. The degree of the increase was slightly higher in the 48-hour-culture than in the 24-hour-one.
The ratio of the low Ca group to the control group for the incorporation of [3H] thymidine into tooth germ was slightly higher in the 48-hour-culture period than in the 24-hour-one.
From these facts, it was suggested that this phenomenon seemed to be one of cell responses in tooth germ, keeping a normal cell function due to increase of cell differentiation and proliferation against a low calcium environment.
