Structure of the protonephridium (excretory organ) of a flatworm. A, part of the excretory apparatus…
Structure of the protonephridium (excretory organ) of a shark. Labels: Wtr, ciliated funnels; Ug, segmental…
Structure of the protonephridium (excretory organ) of an annelid. Labels: Wtr, ciliated funnels; Ds,…