( ( In ( ( the ( circulatory system ) ) ( of animals ) ) ) ( , ( ( a ( portal ( venous system ) ) ) ( ( occurs ( when ( ( a ( capillary bed ) ) ( ( ( ( pools ( into ( another ( capillary bed ) ) ) ) ( through veins ) ) , ) ( without ( first ( going ( through ( the heart ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NP (DT the) (JJ circulatory) (NN system)) (PP (IN of) (NP (NNS animals))))) (, ,) (NP (DT a) (JJ portal) (NNS venous) (NN system)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (JJ capillary) (NN bed)) (VP (VBD pools) (PP (IN into) (NP (DT another) (JJ capillary) (NN bed))) (PP (IN through) (NP (NNS veins))) (, ,) (PP (IN without) (S (ADVP (RB first)) (VP (VBG going) (PP (IN through) (NP (DT the) (NN heart)))))))))) (. .)))
In the circulatory system of animals, a portal venous system occurs when a capillary bed pools into another capillary bed through veins, without first going through the heart.
(ROOT (S (NP (JJ Portal) (NNS veins)) (VP (VBP carry) (NP (NP (NN blood)) (PP (IN between) (NP (NP (NNS pairs)) (PP (IN of) (NP (JJ capillary) (NNS beds))))))) (. .)))