title: Post-larval development of the commercial sponge Spongia officinalis L. (Porifera, Demospongiae).
abstract: This study investigated the development of the larvae of Spongia officinalis in experimental conditions, after settlement on plastic substrates, using electron and light microscopy. The released larvae show a dark pigmented ring distinguishes the posterior larval pole. The youngest larvae, covered with a flagellate epithelium, move onwards by rotating on their longitudinal axis. Over time a creeping-like motion prevails, probably linked to the need for settlement. After a free-swimming period of 24-48 h, larvae settle on the artificial substrate by the anterior pole. At settlement, the flagellate epithelium is substituted by flattened cells, which delimit the outermost surface. Post-larvae were reared to about three months. The early phase of post-larval differentiation shows a solid interior mainly consisting of granular cells varying in shape and size. They are included in a dense collagen matrix that contains a conspicuous amount of bacteria. Lacunae are already evident in the initial phase of metamorphosis. In several of them, cell debris and nucleate cells are visible. This feature is consistent with a progressive reduction of the cell mass (autolysis). Neither choanocyte chambers nor canals differentiate. The morphogenetic process leads to a metamorph only consisting of vacuolated cells and collagen fibrils included in a thin fibrous coat.
authors.affiliation: Università degli Studi di Perugia, Dipartimento di Biologia Cellulare e Ambientale--Via Elce di Sotto--06123 Perugia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Gaino
authors.forename: R
authors.initials: R
authors.lastname: Baldacconi
authors.forename: G
authors.initials: G
authors.lastname: Corriero
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D003094:Collagen / Q000502:physiology / Q000648:ultrastructure; D004847:Epithelial Cells / Q000502:physiology / Q000648:ultrastructure; D005407:Flagella / Q000502:physiology / Q000648:ultrastructure; D007814:Larva / Q000254:growth & development* / Q000648:ultrastructure*; D008124:Locomotion / Q000502:physiology; D008675:Metamorphosis, Biological / Q000502:physiology*; D046529:Microscopy, Electron, Transmission; D011161:Porifera / Q000254:growth & development* / Q000648:ultrastructure*; D013550:Swimming / Q000502:physiology; D014617:Vacuoles / Q000502:physiology / Q000648:ultrastructure