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Ganoine or ''ganoin'' is a glassy, often multi-layered mineralized tissue (biology), tissue that covers the Fish scale, scales, cranium, cranial bones and fish fin, fin rays in some non-teleost Actinopterygii, ray-finned fishes, such as gars, bichirs, and coelacanths. It is composed of rod-like, pseudoprismatic apatite crystallites, with less than 5% of organic matter. Existing fish groups featuring ganoin are bichirs and gars, but ganoin is also characteristic of several extinct taxon, taxa. It is a characteristic component of ganoid scales.
Ganoine is an ancient feature of ray-finned fishes, being found for example on the scales of stem group actinopteryigian ''Cheirolepis''. While often considered a synapomorphy, synapomorphic character of ray-finned fishes, ganoine or ganoine-like tissues are also found on the extinct acanthodii.
It has been suggested that ganoine is homology (biology), homologous to tooth enamel in vertebrates or even considered a type of enamel. Ganoine indeed contains amelogenin-like proteins and has a mineral content similar to that of tetrapod tooth enamel.
Ganoine or ''ganoin'' is a glassy, often multi-layered mineralized tissue (biology), tissue that covers the Fish scale, scales, cranium, cranial bones and fish fin, fin rays in some non-teleost Actinopterygii, ray-finned fishes, such as gars, bichirs, and coelacanths. It is composed of rod-like, pseudoprismatic apatite crystallites, with less than 5% of organic matter. Existing fish groups featuring ganoin are bichirs and gars, but ganoin is also characteristic of several extinct taxon, taxa. It is a characteristic component of ganoid scales.
Ganoine is an ancient feature of ray-finned fishes, being found for example on the scales of stem group actinopteryigian ''Cheirolepis''. While often considered a synapomorphy, synapomorphic character of ray-finned fishes, ganoine or ganoine-like tissues are also found on the extinct acanthodii.
It has been suggested that ganoine is homology (biology), homologous to tooth enamel in vertebrates or even considered a type of enamel. Ganoine indeed contains amelogenin-like proteins and has a mineral content similar to that of tetrapod tooth enamel.
References
{{diversity of fish Fish anatomy Tissues (biology)