( ( Its synthesis ) ( ( begins ( at ( ( ( about 24 ) weeks ) ( of ( gestation ( in ( the ( human fetus ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP$ Its) (NN synthesis)) (VP (VBZ begins) (PP (IN at) (NP (NP (QP (RB about) (CD 24)) (NNS weeks)) (PP (IN of) (NP (NP (NN gestation)) (PP (IN in) (NP (DT the) (JJ human) (NN fetus)))))))) (. .)))
Its synthesis begins at about 24 weeks of gestation in the human fetus.
(ROOT (S (NP (NP (DT The) (NN development)) (PP (IN of) (NP (NP (DT the) (JJ respiratory) (NN system)) (PP (IN in) (NP (DT the) (NN fetus)))))) (VP (VBZ begins) (PP (IN at) (NP (QP (RB about) (CD 4)) (NNS weeks)))) (. .)))
The development of the respiratory system in the fetus begins at about 4 weeks.