( ( The islets ) ( ( are ( ( endocrine tissue ) ( containing ( ( four types ) ( of cells ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS islets)) (VP (VBP are) (NP (NP (JJ endocrine) (NN tissue)) (VP (VBG containing) (NP (NP (CD four) (NNS types)) (PP (IN of) (NP (NNS cells))))))) (. .)))
The islets are endocrine tissue containing four types of cells.
(ROOT (S (NP (NP (CD Four) (NNS types)) (PP (IN of) (NP (NN tissue)))) (VP (VBP are) (VP (VBN found) (PP (IN in) (NP (NNS animals))))) (. .)))