The zebrafish has become an increasingly popular model for studies on the genetics, molecular biology and developmental biology of vertebrates. As all carps, zebrafish lack an oral dentition hut have instead a well developed pharyngeal dentition. We examined the tooth development and the generation of the tooth pattern in several specimens going from 2 to 20 days post fertilisation (dPF), using a wide scope of techniques such as LM, TEM, in toto staining and 3D-reconstructions. During early post-embryonic development, zebrafish teeth are initiated according to a predictable, bilaterally symmetrical pattern, from shortly before hatching (48 hours) onwards. Due to the first one-sided shedding at 14 d PP, the first asymmetry appears. For juveniles up to 20 d PP the tooth pattern shows more and more differences between and within animals (bilateral asymmetry). In general, the older juvenile dentition consists of three tooth rows one of which (the ventral, major row) has five teeth, while the two dorsal, minor rows have less teeth each. This pattern is also persistent in adults, but the number of teeth is less than in juveniles. These results confirm earlier literature reports that larval and juvenile cyprinids have consider- ably more teeth than the adults, apparently due to the prolonged retention of functional teeth that were to be replaced. Tooth morphogenesis, cytodifferentiation, attachment and eruption in this model organism show some different, particular features. The dental lamina can originate directly from the pharyngeal epithelium or from the dental lamina of another tooth, which has implications for the concept of tooth families. These results provide the basic data needed to investigate the role of various factors during odontogenesis. |
