Growth of the tooth germ in new born rats exposed to oxygen at atmospheric and high pressure.

The exposure of adult rats to oxygen at high pressure precipitates convulsive seizures.12 It seems that such exposures have an increased growth effect on the incisor3 and on the tooth germ of rat embryos in the uterus of mothers subjected to such seizures.4 In contrast, intermittent exposures to oxygen at atmospheric pressure promotes increased body weight of adult rats and embryos,3-5 but does not modify the growth rate of either the incisors or the tooth germ.34 We have suggested3,4 that this increased growth rate of the incisors and of the tooth germ may have been caused by the adrenal glands. It is recognized generally that adrenal glands have a protective influence in stress conditions; however, in contrast to this, adrenalectomy affords some protection against the stress of oxygen at high pressure.6 Newborn rats (in which the adrenal glands are not fully developed) were used to test the hypothesis that alteration of tooth germ growth by oxygen at high pressure is caused by the adrenal glands. Experiments were carried out to determine whether oxygen at atmospheric pressure or oxygen at high pressure modifies the growth