Fluoride and iron concentrations in the enameloid of lower teleostean fish.

Our quantitative elemental analyses with the electron microprobe indicated that the fluoride and iron concentrations in the enameloid of bony fish are related to the phylogeny of fish. The enameloid of some bony fish with high F also contained high Fe. In order to clarify the phylogenetic significance of such a peculiar dual deposition of F and Fe into developing enameloid, quantitative electron microprobe analyses of these elements were made on the teeth of taxonomically lower teleosts. There were significantly different trends of F and Fe concentrations in the enameloid among various forms of lower teleosts. In the Osteoglossiformes, the enameloid of the osteoglossid species contained very low levels of F and Fe, whereas in the single representative of the Mormyroidei, the F was very low but Fe was very high. In the Elopomorpha, the enameloid of the elopiform species contained a medium level of F and high Fe, and that of the anguilliform high levels of F and Fe. In the Salmoiformes, the salmonid species had medium F and high Fe, and in a species of the Esocidae, high F and high Fe levels were found. The stomiiform fish exhibited levels of medium and high F and high Fe. The results of the present study and our previous investigations made on archaic non-teleostean and various teleostean fish indicate that the mechanisms of F and Fe concentrations into developing enameloid are independent of each other, and that the mechanisms of Fe concentration appeared earlier and disappeared later than, or concurrently with, that of the F concentration, in the course of fish evolution.