( ( ( Rhythmic ( ( opening and ) closing ) ) ( of ( vesicles ( during constitutive ) ) ) ) ( ( ( ( exo - ) and ) ( endocytosis ( in ( chromaffin cells ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Rhythmic) (NN opening) (CC and) (NN closing)) (PP (IN of) (NP (NP (NNS vesicles)) (PP (IN during) (NP (NN constitutive)))))) (VP (VP (VBP exo)) (: -) (CC and) (VP (VBZ endocytosis) (PP (IN in) (NP (NN chromaffin) (NNS cells))))) (. .)))
Rhythmic opening and closing of vesicles during constitutive exo- and endocytosis in chromaffin cells.
(ROOT (S (NP (NNS Vesicles)) (VP (VBP are) (VP (VBN used) (PP (IN during) (NP (NNS endocytosis))) (S (VP (TO to) (VP (VB allow) (S (NP (NNS molecules)) (VP (TO to) (VP (VB enter) (NP (DT the) (NN cell)))))))))) (. .)))