( ( By ( 5 weeks ) ) ( , ( ( the baby ) ( ( has ( ( ( a layer ) ( of skin ) ) ( that ( is ( ( ( only 1 ) cell ) thick ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN By) (NP (CD 5) (NNS weeks))) (, ,) (NP (DT the) (NN baby)) (VP (VBZ has) (NP (NP (DT a) (NN layer)) (PP (IN of) (NP (NN skin))) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (ADJP (NP (QP (RB only) (CD 1)) (NN cell)) (JJ thick))))))) (. .)))
By 5 weeks, the baby has a layer of skin that is only 1 cell thick.
(ROOT (S (NP (NP (DT The) (JJ thick) (NN skin)) (, ,) (VP (VBN found) (ADVP (RB only)) (PP (IN on) (NP (NP (NP (DT the) (NNS palms)) (PP (IN of) (NP (DT the) (NNS hands)))) (CC and) (NP (NP (DT the) (NNS soles)) (PP (IN of) (NP (DT the) (NNS feet))))))) (, ,)) (VP (VBZ has) (NP (DT an) (JJ extra) (NN layer))) (. .)))