| Popis: |
Skeletal tissues represent a key novelty of vertebrates, moreover, structural diversification and phenotypic adaptation of cartilaginous, bony and dental elements determine life strategies of each vertebrate lineage. Ray-finned fishes (Actinopterygii) constitute the most diverse vertebrate group with striking diversity in skeletogenesis and skeletal systems. In this thesis, comparative developmental analyses of craniofacial skeletal tissues and structures in bichirs (Polypteriformes) and sturgeons (Acipenseriformes), was analysed. These basal lineages differ essentially in their strategy of skeletogenesis. Bichirs represent heavily armoured forms with massive exoskeleton, they also comprise thick ganoid scales and dental structures that cover the whole oropharynx. Sturgeons, on the contrary, are primarily cartilaginous fishes with rather reduced skeleton and with teeth that are completely lost during larval development. Skeletogenesis was studied on a unique series of embryonic and larval stages of the Senegal bichir (Polypterus senegalus) and the sterlet (Acipenser ruthenus) by whole-mount staining of their cartilage and mineralized tissues followed by fluorescent microscopy visualisation. Growth dynamics of their skeletal systems was described and compared; expansion of their bony surfaces during ontogeny... |
