The protonephridial system of the tusk shell, Antalis entalis (Mollusca, Scaphopoda)

Abstract The development and microanatomy of the protonephridial system in larvae and postmetamorphic juveniles of Antalis entalis (Dentaliidae) have been examined by means of a semithin serial sectioning and reconstruction technique. One late larval stage has been additionally examined by transmiss...

Full description

Saved in:
Bibliographic Details
Published in:Zoomorphology 2001-06, Vol.121 (1), p.19-26
Main Authors: Ruthensteiner, B., Wanninger, Andreas, Haszprunar, Gerhard
Format: Article
Language:English
Subjects:
Antalis entalis
Cytoplasm
Electron microscopy
Juveniles
Larvae
Larval development
Larval stage
Metamorphosis
Mitochondria
Mollusca
Mollusks
Polyploidy
Sectioning
Transmission electron microscopy
Ultrafiltration
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract The development and microanatomy of the protonephridial system in larvae and postmetamorphic juveniles of Antalis entalis (Dentaliidae) have been examined by means of a semithin serial sectioning and reconstruction technique. One late larval stage has been additionally examined by transmission electron microscopy. The protonephridium appears during larval development and is reduced in the juvenile approximately 13 days after metamorphosis. This is the first unambiguous evidence of a protonephridium in a postlarval mollusc. When fully developed the protonephridium is unique in consisting of two cells only, a terminal cell (=cyrtocyte) and a duct-releasing cell with glandular appearance. The polyciliary terminal cell has several distinct ultrafiltration sites, resembling conditions in bivalve protonephridia. The large duct-releasing cell shows a very large nucleus probably reflecting polyploidy. Its basal infoldings and many mitochondria suggest metabolic activity, the cytoplasm is characterised by many distinct granules. The unique features of the scaphopod protonephridial system are compared with available data on the protonephridia of other molluscan classes. The finding gives additional evidence that protonephridia belong to the ground pattern of the Mollusca.
ISSN:0720-213X
1432-234X
DOI:10.1007/s004350100040