3)collecting tubule arched collecting tubules 6/a cortical collection tubules medullary collection tubules simple cuboidal epi. to simple columnar epi slight-stained have clear boundary -reabsorb 4% water3) collecting tubule: arched collecting tubules cortical collection tubules medullary collection tubules -simple cuboidal epi. to simple columnar epi. -slight –stained -have clear boundary -reabsorb 4% water