part_of part of part of contained in develops from existence overlaps material entity Stage 6 Stage 7 Stage 8 protonephridial progenitor cell protonephridia PMID:21937596 PMID:27150006 PMID:27551436 PMID:19852954 PMID:26651295 ISBN:9780070316607 https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407 nephridia Planarian_Anatomy PMID:29674431 PMID:26057828 PMID:24063805 PMID:24523458 PMID:19933103 PMID:29674432 PMID:28292427 UBERON:0006973 PMID:27068018 PMID:23954785 PMID:29100657 OCLC:16809160 PMID:21828097 PMID:25254346 PMID:23318641 PMID:28245923 PMID:25017721 osmoregulatory duct Excretory organs consisting of flame cells, proximal tubules, and distal tubules connected to a mesenchymal collecting duct. PMID:29158443 PMID:27612384 PMID:28807897 PMID:26457503 excretory organ PMID:23318635 PMID:22479207 PMID:26711341 PMID:27501047 PMID:24992682 protonephridial tubule PMID:24737865 renal system anterior region of the whole animal dorsal region of the whole animal posterior region of the whole animal juvenile stage head region prepharyngeal region parapharyngeal region tail region organ adult hermaphrodite asexual adult copulatory region