( ( This accumulation ) ( ( ( results ( from ( ( the ability ) ( of ( ( highly lipophilic ) substances ) ) ) ) ) ( ( ( to ( dissolve ( in ( ( the ( lipid membrane ) ) ( of ( epithelial cells ) ) ) ) ) ) and ) ( to ( be ( ( retained ( in ( ( the body ) ( via ( their ( passive transport ) ) ) ) ) ) ( back ( across ( the epithelium ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This) (NN accumulation)) (VP (VBZ results) (PP (IN from) (NP (NP (DT the) (NN ability)) (PP (IN of) (NP (ADJP (RB highly) (JJ lipophilic)) (NNS substances))))) (S (VP (VP (TO to) (VP (VB dissolve) (PP (IN in) (NP (NP (DT the) (NN lipid) (NN membrane)) (PP (IN of) (NP (JJ epithelial) (NNS cells))))))) (CC and) (VP (TO to) (VP (VB be) (VP (VBN retained) (PP (IN in) (NP (NP (DT the) (NN body)) (PP (IN via) (NP (PRP$ their) (JJ passive) (NN transport))))) (PP (ADVP (RB back)) (IN across) (NP (DT the) (NN epithelium))))))))) (. .)))
This accumulation results from the ability of highly lipophilic substances to dissolve in the lipid membrane of epithelial cells and to be retained in the body via their passive transport back across the epithelium.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NNS substances)) (VP (VBP pass) (PP (IN through) (NP (DT the) (NN cell) (NN membrane))) (PP (IN without) (S (VP (VBG needing) (NP (DT any) (NN energy)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (VP (VBN called) (NP (JJ passive) (NN transport)))) (. .)))