Fine structural comparative peculiarities of the developing dipnoan dermal skeleton in the fins of Neoceratodus larvae.

This study shows that actinotrichia are present in the growing fins of the dipnoan larvae Neoceratodus . They develop in advance of the camptotrichia , which will finally sustain the adult fin. Actinotrichia in dipnoan fins are similar to those already described in other osteichthyans . This feature strongly suggests the plesiomorphic character of the actinotrichia in the fish fins. In dipnoan , unlike other osteichthyan , actinotrichia are integrated in the growing camptotrichia and thus disappear in the adult fin. Consequently, only in dipnoan are actinotrichia a transitory dermal skeleton.