Some remarks on the axial skeleton in Protopterus (Pisces, Dipnoi).
Based on a comparative morphological study of the axial skeleton in a broader range of "primitive bony fishes" a reevaluation of some characteristic traits of the vertebral column in the African lungfish has been done. The axial skeleton of living dipnoans has to be regarded as reduced from a more complex phylogenetic state and may be neotenic in some respect. The formation of perichordal bony autocentra could be confirmed, at least in one specimen. The well-known invasion of mesenchymal cells into the fibrous sheet of the notochord is interpreted as a rudimentary chordacentric "vertebralization". Also included is an analysis of the peculiar urostyle of lungfishes, its regeneration capacity and its bearing upon the principles of vertebra-formation.
Bartsch
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Zoologisches Institut, Universität Köln, FRG.
D000818:Animals; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology; D005399:Fishes / Q000033:anatomy & histology*; D009672:Notochord / Q000033:anatomy & histology*; D010802:Phylogeny; D013131:Spine / Q000033:anatomy & histology*