Tooth succession in the zebrafish (Danio rerio).

To test whether the formation of replacement teeth in arbitrarily chosen zebrafish follows the same pattern as described for larval and young zebrafish of known age, dentitions of more than 90 animals of different ages and standard lengths were observed under the stereomicroscope. Only the teeth of the ventral tooth row (1V-5V) were considered. Statistical results (G-tests) suggested that tooth replacement does not occur randomly. The most common order of replacement can be represented as the formula 5V-2V-3V-1V-4V and counts for approximately 70% of the observed patterns. Initiation of replacement teeth at positions 4V and 5V is separated by a larger time interval than between any other combination. It is hypothesized that in older juveniles and adults, replacement teeth may be formed during three odontogenic waves.