( ( In ( the ( secondary ( cell wall ) ) ) ) ( , ( ( the ( cellulose microfibrils ) ) ( ( ( ( are criss-crossed ) and ) ( are ( impregnated ( with ( ( lignin , ) ( ( both ( of which ) ) ( make ( ( secondary ( cell walls ) ) ( very ( ( hard and ) rigid ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (DT the) (JJ secondary) (NN cell) (NN wall))) (, ,) (NP (DT the) (NN cellulose) (NNS microfibrils)) (VP (VP (VBP are) (ADJP (JJ criss-crossed))) (CC and) (VP (VBP are) (VP (VBN impregnated) (PP (IN with) (NP (NP (NN lignin)) (, ,) (SBAR (WHNP (DT both) (WHPP (IN of) (WHNP (WDT which)))) (S (VP (VBP make) (S (NP (JJ secondary) (NN cell) (NNS walls)) (ADJP (RB very) (JJ hard) (CC and) (JJ rigid))))))))))) (. .)))
In the secondary cell wall, the cellulose microfibrils are criss-crossed and are impregnated with lignin, both of which make secondary cell walls very hard and rigid.
(ROOT (S (NP (DT The) (JJ secondary) (NN wall)) (VP (VBZ contains) (NP (NP (NN lignin)) (, ,) (NP (NP (DT a) (JJ secondary) (NN cell) (NN component)) (PP (IN in) (NP (NN plant) (NNS cells))) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (VP (VBN completed) (NP (NN cell) (NN growth/expansion))))))))) (. .)))