Comparative study on the morphology and the composition of the otoliths in the teleosts

Conclusion. Saccular otoliths of teleosts were mostly larger than utricular otoliths, which might relate to the three-dimensional movement. The large and heavy otolith may be better suited in saccules of the bottom and reef fishes. The quantities of iron in lagenar otoliths were found to be lower than those of birds. The function of the fish lagena remains to be elucidated by further studies. Objective. To evaluate the morphological characteristics and the chemical composition of the otoliths in fishes as related to behaviour and habitat. Materials and methods. We studied the morphology of the otoliths of 18 genera of fishes (81 samples) divided into 3 groups: saltwater fish (13 genera), freshwater fish except for the carp family (3 genera) and carp family fish (2 genera). The otoliths and the living environments were compared. The chemical composition was analysed using a synchrotron X-ray fluorescence analyser. Results. Bottom fishes generally have larger saccular otoliths, and migrating fishes have smaller saccular otoliths. In comparing the bottom/reef fishes and the migrating fishes in salt water, the former tended to have larger saccular otoliths. In saltwater bottom fishes the tendency was found that the thinner the head, the larger was the saccular otolith. We found significant quantities of iron, zinc and manganese in the lagenar otoliths.     

Comparative study on the morphology and the composition of the otoliths in the teleosts

CONCLUSION: Saccular otoliths of teleosts were mostly larger than utricular otoliths, which might relate to the three-dimensional movement. The large and heavy otolith may be better suited in saccules of the bottom and reef fishes. The quantities of iron in lagenar otoliths were found to be lower than those of birds. The function of the fish lagena remains to be elucidated by further studies. OBJECTIVE: To evaluate the morphological characteristics and the chemical composition of the otoliths in fishes as related to behaviour and habitat. MATERIALS AND METHODS: We studied the morphology of the otoliths of 18 genera of fishes (81 samples) divided into 3 groups: saltwater fish (13 genera), freshwater fish except for the carp family (3 genera) and carp family fish (2 genera). The otoliths and the living environments were compared. The chemical composition was analysed using a synchrotron X-ray fluorescence analyser. RESULTS: Bottom fishes generally have larger saccular otoliths, and migrating fishes have smaller saccular otoliths. In comparing the bottom/reef fishes and the migrating fishes in salt water, the former tended to have larger saccular otoliths. In saltwater bottom fishes the tendency was found that the thinner the head, the larger was the saccular otolith. We found significant quantities of iron, zinc and manganese in the lagenar otoliths.     

Contribution to the development of the union between the manubrium of the malleus and the tympanic membrane in human fetus

The development of the union between the manubrium of the malleus and the tympanic membrane was studied in human embryo. For that purpose 25 temporal bones of human foetus, aged from 36 days (14 mm) to 29 weeks (270 mm) were analyzed. Samples were fixed in a 10% formaldehyde solution, decalcified with 2% nitric acid, embedded in Paraplast, cut in sections of 7 microns thick and stained with Martin's trichrome method. During the development a pseudojoint between the malleus and the tympanic membrane several stages were seen. In the first stage, the manubrium was adhered to membrane mesenchyme of primitive tympanum, in the second one this mesenchyme was loose and there appeared capillars in it, in the third one there were collagen fibers in a radial disposition, and in the forth stage, the hollow in the meatal plug gave independence to the tympanic membrane for the external acoustic meatus. The distal portion of the manubrium, included in tympanic membrane, has remained with a cartilaginous structure during end of the time it has been studied by us. The collagen fibers at the level of the umbo surround the manubrium, while the rest of it remains in its anterior edge.