CHANGES IN THE RAT INCISOR FOLLOWING BILATERAL ADRENALECTOMY

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Abstract
Complete adrenalcctomy (rat) causes disturbance in calcification of dentin. Characteristic changes occur in the predentin of the incisors. These changes are manifested by the presence of globules disseminated throughout the predentin of the middle third of the incisor. The "globular predentin" stains, with eosin and hematoxylin, like intermediate dentin. It was not present in nearly 1000 rats that were studied in other investigations, in which adrenalcctomy was not performed, except in 3 animals that were given single doses of parathyroid extract and examined 19 hrs. later. Other evidences of disturbed calcification in the dentin are the deep staining of the labial dentin by hematoxylin and prominent stratification in the lingual dentin. In adrenalcctomized animals that survived up to about 10 days the post-operative dentin could be distinguished from the pre-operative by the presence of a deeply stained band corresponding to the portion of dentin that was laid down and calcified about the time of the operation. The presence of this band permits measurements of the post-operative dentin from which can be calculated the survival period of the animal. In adrenalcctomized rats whose survival was prolonged by the presence of accessory adrenal bodies, the characteristic globular predentin was absent. They showed changes similar to those found in rickets, viz., wide predentin (40-84[mu]) and prominent interglobular dentin. This observation suggests the probability of a relation of disturbed adrenal function to the Ca disturbances associated with the development of rickets. The results obtained in these expts. afford interesting information on calcification processes of enamel and dentin. In a small number of animals the enamel-forming cells (ganoblasts) showed intracellular globules which stained deeply with hematoxylin. Occurrence of globular predentin in the 3 animals that were subjected to the action of parathyroid extract confirms the observation that adrenal insufficiency is associated with disturbances in Ca metabolism (Rogoff and Stewart, 1928), and lends support to the suggestion of a functional interrelationship between the adrenal and parathyroid glands [see in this issue entry 10915]. Although evidence favors the probability that the adrenal cortex is primarily involved, the possible relation of the medulla has not been excluded.