Tooth replacement in the upper jaw of the rainbow trout (Salmo gairdneri).

The present paper describes the pattern of tooth replacement in the upper jaw of two size ranges of rainbow trout (standard lengths 12-15 cm and 20-23 cm) as determined from wax impressions of the dentitions taken twice weekly on anaesthetised fish. There was considerable variation in the nature of replacement waves (lines constructed on dental charts linking eruption times of alternate teeth) between fish for both the premaxillary/maxillary and vomerine/palatine rows. The wave patterns obtained showed the same consistency of form for any one animal which is to be expected when consecutive generations show constant or proportionately changing life spans. Data relating to the life span of the teeth is given. The results are compared with those derived for the lower jaw and the significance of wave form discussed.