(S (S (NP (BASENP (DT The) (NN study)) (PRN (COMMA ,) (VP (VBN led) (PP (IN by) (NP (NP (NNP Drs.) (NP (BASENP (NNP Samuel) (NNP Weiss)) (CC and) (BASENP (NNP V.) (NNP Wee) (NNP Yong)))) (PP (IN of) (BASENP (DT the) (NNP Hotchkiss) (NNP Brain) (NNP Institute)))))) (COMMA ,))) (VP (VBD compared) (NP (BASENP (ADJP (JJ virgin) (CC and) (JJ pregnant)) (NNS mice)) (PP (IN with) (NP (BASENP (JJ MS-like) (NNS lesions)) (VP (VBN introduced) (PP (IN by) (NP (BASENP (NN lysolecithin)) (COMMA ,) (NP (BASENP (DT a) (NN chemical)) (SBAR (WHNP (WDT which)) (S (VP (VBZ destroys) (NP (BASENP (DT the) (JJ myelin) (NNS sheaths)) (PP (IN around) (BASENP (NNS neurons)))))))))))))))) (PERIOD .))