( Osteoclasts ( normally ( ( do ( this ( to ( ( ( ( break down ) ( ( ( ( old ( bone tissue ) ) and ) then ) ( osteoblasts ( come in ) ) ) ) and ) ( make ( new tissue ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NNS Osteoclasts)) (ADVP (RB normally)) (VP (VBP do) (S (NP (DT this)) (VP (TO to) (VP (VP (VB break) (PRT (RP down)) (NP (NP (JJ old) (NN bone) (NN tissue)) (CC and) (ADVP (RB then)) (NP (NP (NNS osteoblasts)) (VP (VBN come) (PP (IN in)))))) (CC and) (VP (VB make) (NP (JJ new) (NN tissue))))))) (. .)))
Osteoclasts normally do this to break down old bone tissue and then osteoblasts come in and make new tissue.
(ROOT (S (NP (NNS Bones)) (VP (VBP are) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NNS tissues))))) (. .)))