, Volume 107, Issue 2, pp 88–95 | Cite as

Ultrastructure of the lycophora larva of Gyrocotyle urna (Cestoda, Gyrocotylidea)

III. the protonephridial system
  • W. E. R. Xylander


The ultrastructure of the protonephridial system of the lycophore larva of Gyrocotyle urna Grube and Wagener, 1852, is described. It consists of six terminal cells, at least two proximal canal cells, two distal canal cells and two nephridiopore cells. The terminal cells and the proximal canal cell build up the filtration weir with its two circles of weir rods. The proximal canal cell constitutes a solid, hollow cylinder without a cell gap and desmosome. The distal canal cell is characterized by a strong reduction of the canal lumen by irregularly shaped microvilli. The nephridiopore region is formed by a nephridiopore cell; its cell body is located at some distance proximally within the larva. The connection among different canal cells is brought about by septate desmosomes. Morphological, evolutionary and functional aspects of the protonephridial system within Platyhelminthes are discussed. The structure of the proximal canal cells without a desmosome is considered an autapomorphy of Cestoda.


Developmental Biology Cell Body Strong Reduction Hollow Cylinder Functional Aspect 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



cilia of the terminal cell


distal canal cell


lumen of the distal canal cell




outer rods of the filtration weir


inner leptotriches


inner rods of the filtration weir


lipid droplets






nephridiopore cell


neodermis anlage cells




proximal canal cell


ciliary rootlets


septate desmosome


terminal cell


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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • W. E. R. Xylander
    • 1
    • 2
  1. 1.II. Zoologisches Institut der Universität GöttingenGöttingenFederal Republic of Germany
  2. 2.Institut für Allgemeine und Spezielle Zoologie der Justus-Liebig-UniversitätGießenFederal Republic of Germany

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