title: Similarity in yolk-platelet structure of an ancient bony fish (Acipenser) and an ancient reptile (Sphenodon).
abstract: Lipovitellin-phosvitin crystals from oocytes of the sturgeon (Acipenser boeri L.) and the tuatara (Sphenodon punctatus [Gray]) have been shown to he orthorhombic like all such known crystals from vertebrates higher than cyclostomes. Lattice parameters and projected crystal views also resembled closely the hitherto known cases. The high evolutionary conservation of this crystal structure probably reflects a cell-biological significance of the tertiary structure of crystal constituents, especially of the lipovitellines. A comparative consideration of crystallographic data from cyclostomes and higher vertebrates suggests that cyclostomes started with one species and all higher vertebrates with two species of lipovitellin molecules.
authors.affiliation: Institute of Anatomy and Cell Biology, University of Giessen, D-6300 Giessen, Federal Republic of Germany.
authors.forename: R H
authors.initials: RH
authors.lastname: Lange
authors.forename: W
authors.initials: W
authors.lastname: Kilarski