title: Condensation rhythm of fresh-water sponges (Spongillidae, Porifera).
abstract: The mesenchyme continuum of spongillids exhibits rhythmic changes that at first glance appear to be contractions. Actually, however, the process is a condensation initiated by the formation of punctate cell contacts and a rapid swelling of all mesenchymal cells. As the cells come into closer contact and the spaces between them are constricted, the volume of the mesenchyme shrinks, giving the impression of a contraction. It seems likely that rhythmic mesenchyme condensation assists the choanocyte chambers in pumping water through the sponge.
authors.affiliation: Entwicklungsgeschichtliche Abteilung, Zoologischen Instituts der Universität, Bonn/Bundesrepublik Deutschland.
authors.forename: N
authors.initials: N
authors.lastname: Weissenfels
mesh_terms: D000818:Animals; D010507:Periodicity; D011161:Porifera / Q000166:cytology / Q000502:physiology*; D014867:Water / Q000502:physiology
chemical_list: D014867:Water