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Ultrastructural evidence of extruding exocytosis of residual bodies in the freshwater sponge Ephydatia fluviatilis
Author(s) -
Willenz Philippe,
van de Vyver Gysèle
Publication year - 1986
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051900307
Subject(s) - vacuole , biology , ultrastructure , budding , exocytosis , membrane , biophysics , vesicle , microbiology and biotechnology , cell wall , organelle , cell membrane , cytoplasm , anatomy , biochemistry
Exocytosis of residual bodies by choanocytes, archeocytes and endopinacocytes lining the aquiferous system of Ephydatia fluviatilis has been demonstrated using calibrated latex beads and Escherichia coli as tracers. In passing into the mesohyl or the lumen of the exhalant aquiferous canals, beads, and altered bacteria were enveloped by the plasma membrane of the cell containing them. The membrane constricted at a neck region to form extruding vacuoles. This process appeared first in choanocytes and later in other cell types. The occurrence of these buds increased with the length of incubation time, as did the number of particles they contained. Acid phosphatase activity was frequently associated with the particles budding from the cell membrane, confirming that this process followed digestive activity. Membranous vacuoles were recovered from the external medium and observed by TEM and those adhering to the substratum were seen by SEM. These observations proved that vacuoles were released from the sponges. This membrane‐consuming mechanism of exoctyosis implies intense membrane replacement in the digestive cells of the sponge.