title: Microanatomy and ultrastructure of the protonephridial system in the larva of the limpet, Patella vulgata L. (Mollusca, Patellogastropoda).
abstract: The microanatomy and ultrastructure of the larval excretory system of Patella vulgata L., 1758 has been examined by means of semithin and ultrathin serial sections, reconstructions, and transmission electron microscopy. The protonephridial system appears after torsion and consists of two terminal flame bulbs with narrow, ciliated ducts. Whereas the polyciliary terminal cells (cyrtocytes) are only slightly asymmetrically placed below the mantle cavity, the distal excretory ducts and their openings show remarkable asymmetry due to torsion. Further larval ultrafiltration sites with identical fine-structure (meandering slits with diaphragms covered by extracellular matrix) are present in the solitary rhogocytes (pore cells). The presence of larval protonephridia is regarded as plesiomorphic for Mollusca and the Trochozoa (Spiralia) as a whole and the specific conditions (asymmetry, simplicity) in Patella are probably plesiomorphic for the Gastropoda.
authors.affiliation: Zoological State Collection, Munich and Institute of Zoology, Ludwig-Maximilians-University, Germany. haszi@zi.biologie.uni-muenchen.de
authors.forename: G
authors.initials: G
authors.lastname: Haszprunar
authors.forename: B
authors.initials: B
authors.lastname: Ruthensteiner
mesh_terms: D000818:Animals; D007668:Kidney / Q000648:ultrastructure; D007814:Larva / Q000648:ultrastructure; D008974:Mollusca / Q000145:classification / Q000648:ultrastructure*