The nucleus of the tube cell has meanwhile passed into the tube, as does also the generative nucleus, which divides ( if it hasn't already ) to form two sperm cells.
12.
The secretory organs of rhabditophorans, the protonephridia, also have a unique anatomy in which the flame cells and tube cells present a series of cytoplasmic projections that overlap, forming a two-cell'weir '.
13.
The tube cells'flagella drive the water towards exits called nephridiopores, while their microvilli re-absorb re-usable materials and as much water as is needed to keep the body fluids at the right level of concentration.
14.
Flame cells, so called because the beating of their flagella looks like a flickering candle flame, extract from the mesenchyme water that contains wastes and some re-usable material, and drive it into networks of tube cells which are lined with flagella and microvilli.
