( ( ( The organization ) ( of ( ( ( the ( gray matter ) ) and ) ( white matter ) ) ) ) ( ( is ( characteristic ( for ( ( each level ) ( of ( the ( brain stem ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN organization)) (PP (IN of) (NP (NP (DT the) (JJ gray) (NN matter)) (CC and) (NP (JJ white) (NN matter))))) (VP (VBZ is) (ADJP (JJ characteristic) (PP (IN for) (NP (NP (DT each) (NN level)) (PP (IN of) (NP (DT the) (NN brain) (NN stem))))))) (. .)))
The organization of the gray matter and white matter is characteristic for each level of the brain stem.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (DT the) (JJ gray) (NN matter)))) (VP (VBZ is) (PP (IN on) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (DT the) (NN brain))))) (, ,) (S (VP (VBG surrounding) (NP (JJ white) (NN matter))))) (. .)))