( ( ( ( ( The medulla ) , ) ( which ( is ( the ( innermost layer ) ) ) ) ) , ) ( ( comprises ( ( a core ) ( of ( soft ( keratin cells ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN medulla)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (DT the) (JJ innermost) (NN layer))))) (, ,)) (VP (VBZ comprises) (NP (NP (DT a) (NN core)) (PP (IN of) (NP (JJ soft) (NN keratin) (NNS cells))))) (. .)))
The medulla, which is the innermost layer, comprises a core of soft keratin cells.
(ROOT (S (NP (DT The) (DT the) (NN core)) (VP (VBZ is) (NP (NP (DT the) (JJ innermost) (NN layer)) (PP (IN of) (NP (DT the) (NN sun))))) (. .)))