( ( ( A ( complex network ) ) ( of ( ( small ( blood vessels ) ) ( including ( arterioles ( , ( capillaries ( , ( and venules ) ) ) ) ) ) ) ) ) . )
(ROOT (NP (NP (DT A) (JJ complex) (NN network)) (PP (IN of) (NP (NP (JJ small) (NN blood) (NNS vessels)) (PP (VBG including) (NP (NNS arterioles) (, ,) (NNS capillaries) (, ,) (CC and) (NNS venules))))) (. .)))
A complex network of small blood vessels including arterioles, capillaries, and venules.
(ROOT (S (NP (NNS Capillaries)) (VP (VBP are) (NP (NP (DT the) (JJS smallest) (NN type)) (PP (IN of) (NP (NN blood) (NNS vessels))))) (. .)))