Sentence Examples


  • Essentially, a nephridium is a tube, generally very long and much folded upon itself, composed of a string of cells placed end to end in which the continuous lumen is excavated.
  • Frequently the lumen is branched and may form a complicated anastomosing network in these cells.
  • Externally, the nephridium opens by a straight part of the tube, which is often very wide, and here the intracellular lumen becomes intercellular.
  • Rarely the nephridium does not communicate with the coelom; in such cases the nephridium ends in a single cell, like the "flame cell" of a Platyhelminth worm, in which there is a lumen blocked at the coelomic end by a tuft of fine cilia projecting into the lumen.
  • The Polychaeta, however, present us with another form of nephridium seen, for example, in Arenicola, where a large funnel leads into a short and wide excretory tube whose lumen is intercellular.

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