Description:
<jats:title>Abstract</jats:title><jats:p>A histological study was undertaken on the jaws of three rainbow trout (<jats:italic>Salmo gairdneri</jats:italic>) for which the previous dental record of each tooth position had been obtained by taking wax impressions of the jaws twice weekly. This has provided accurate data concerning the time sequence of events in the life cycle of the teeth. The periods of development leading to initial calcification, resorption and exfoliation of its predecessor, and ankylosis were rapid and each was calculated as taking no more than one week out of a life cycle, in the case of a mandibular tooth of a fish of body length 15 cm, of approximately 16 weeks. There was some evidence that resorption of a functioning tooth could commence internally as well as externally. Eruptive movements have to be accomplished rapidly and some contribution appears to be made by an uprighting of the tooth from its angled, developmental position.</jats:p>