title: Ultrastructure and cytochemistry of the early calcification site and of its mineralization organic matrix in Paracentrotus lividus (Echinodermata: Echinoidea).
abstract: The ultrastructure and cytochemistry of skeleton formation sites prior to mineralization are described for the first time in echinoderms. These early sites are intracellular vacuoles located in syncytial pseudopodia of skeleton-forming cells. They contain a mineralization organic matrix, which shows a calcium-binding ability and is framed in a tridimensional structure made of concentric layers bridged by radial threads. This organic matrix presents repetitive structures which could be implicated in mineralization control. Both the tridimensional organization of the organic matrix and its framing, before mineralization starts, question the current theories which suggest that the echinoderm organic matrix is soluble at the onset of mineralization and adsorbs on the forming crystal.
authors.affiliation: Laboratoire de Biologie marine, Université Libre de Bruxelles, Belgium. lameye@ulb.ac.be
authors.forename: L
authors.initials: L
authors.lastname: Ameye
authors.forename: P
authors.initials: P
authors.lastname: Compère
authors.forename: J
authors.initials: J
authors.lastname: Dille
authors.forename: P
authors.initials: P
authors.lastname: Dubois
mesh_terms: D000818:Animals; D000965:Antimony; D002113:Calcification, Physiologic; D004396:Coloring Agents; D004577:Electron Probe Microanalysis; D005404:Fixatives; D006651:Histocytochemistry; D047348:Hydrolyzable Tannins; D008854:Microscopy, Electron; D011554:Pseudopodia / Q000648:ultrastructure; D012430:Ruthenium Red; D012617:Sea Urchins / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure*; D016707:Tissue Fixation; D014617:Vacuoles / Q000648:ultrastructure
chemical_list: D004396:Coloring Agents; D005404:Fixatives; D047348:Hydrolyzable Tannins; D012430:Ruthenium Red; C009002:potassium antimonate; D000965:Antimony