Ultrastructure of the Protonephridia in the Dorvilleid Polychaete Apodotrocha progenerans (Annelida)

The achaetous dorvilleid polychaete Apodotrocha progenerans Westheide & Riser, 1983, possesses several pairs of segmentally arranged protonephridia. They consist of a blindly ending terminal cell and three tubule (emission) cells. The terminal cell is a flame bulb with unusual filtration area consisting of interdigitated pedicel-like projections. Each cell has its own tuft of flagella; and the emission channel is intracellular. The tube-shaped 'seamless' cells are slotted into each other like water-pipes.