Meeting Abstract

P3.61  Saturday, Jan. 5  Morphogenesis during asexual bud-formation and growth in the poriferan Tethya wilhelma: silica skeleton, aquiferous system and the mesohyle HAMMEL, J.U.*; BECKMANN, F.; NICKEL, M.; Institut fuer Spezielle Zoologie und Entwicklungsbiologie, FSU Jena, Germany; GKSS Research Centre, Geesthacht, Germany; Institut fuer Spezielle Zoologie und Entwicklungsbiologie, FSU Jena, Germany Hammel@porifera.net

The highly contractile and locomotory poriferan Tethya wilhelma is a model to investigate early evolved metazoan contractile tissues and coordination mechanisms. The main reproduction mode is asexual. The analysis of the onset of contractile behaviour and response during bud development in correlation to the morphogenesis of the functional body structures of the sponge will help to understand the contractile effector systems. Buds form at the tip of filaments protruding from the globous sponge body. The structural basis of the filaments is a dynamic composite of silica scleres and collagen, representing elongations of bundles of the radial skeleton in this species. During bud formation, a high number of cells, representing various cell types, migrate from the mother sponge along the filaments into the tips. All major spicule types of the siliceous skeleton are transferred into the bud, too and arranged into the typical pattern of three skeletal superstructures during growth of the bud. Here we describe, visualize and quantitatively analyse the related morphogenis of the silica skeleton, aquiferous system and the mesohyle using SEM, synchrotron radiation based x-ray microtomography (SR-�CT) and light microscopy.