( ( ( ( ( Cartilage cells ) , ) ( called chondroblasts ) ) , ) ( ( make cartilage ) . ) )
(ROOT (S (NP (NP (JJ Cartilage) (NNS cells)) (, ,) (VP (VBN called) (NP (NNS chondroblasts))) (, ,)) (VP (VBP make) (NP (NN cartilage))) (. .)))
Cartilage cells, called chondroblasts, make cartilage.
(ROOT (S (NP (NNS Hagfishes)) (VP (VBP have) (NP (NP (DT a) (NN skull)) (VP (VBN made) (PP (IN of) (NP (NN cartilage)))))) (. .)))