( ( opening ( of ( ( ion channels ) ( in ( the egg ) ) ) ) ) ( membrane . ) )
(ROOT (S (NP (NP (NN opening)) (PP (IN of) (NP (NP (NN ion) (NNS channels)) (PP (IN in) (NP (DT the) (NN egg)))))) (VP (VBZ membrane)) (. .)))
opening of ion channels in the egg membrane.
(ROOT (NP (NP (NP (NNP Ion) (NNP channels) (NNP facilitate)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-))) (NP (NP (DT the) (NN diffusion)) (PP (IN of) (NP (NP (NNS ions)) (PP (IN across) (NP (DT a) (NN membrane)))))) (. .)))