title: [Differentiation processes in the germinating Gemmula ofEphydatia fluviatilis].
abstract: The dormant shelled gemmulae of the fresh water spongeEphydatia fluviatilis contain uniform, totipotent statocytes (thésocytes), which can differentiate either into archaeocytes (mono- and binucleated) or into histoblasts. The histoblasts accumulate at the villus near the micropyle. The other cell types orientate in a three-dimensional pattern at the micropyle, according to a developing gradient.After the primary pinacoderm is formed, the sponge primordium is released through the open micropyle. The primordium develops into a new sponge, into which archaeocytes, histoblasts and scleroblasts migrate.
authors.affiliation: Zoologisches Institut der Universität Bonn, Poppelsdorfer Schloß, D-5300, Bonn, Germany.
authors.forename: Doris
authors.initials: D
authors.lastname: Höhr
keywords: Cell differentiation; Development; Gemmula; Porifera; Spongillides