( ( During ( ( the ( third week ) ) ( of ( embryonic growth ) ) ) ) ( ( the brain ) ( ( begins ( to ( develop ( in ( ( the ( early fetus ) ) ( in ( ( a process ) ( called induction ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN During) (NP (NP (DT the) (JJ third) (NN week)) (PP (IN of) (NP (JJ embryonic) (NN growth))))) (NP (DT the) (NN brain)) (VP (VBZ begins) (S (VP (TO to) (VP (VB develop) (PP (IN in) (NP (NP (DT the) (JJ early) (NN fetus)) (PP (IN in) (NP (NP (DT a) (NN process)) (VP (VBN called) (NP (NN induction))))))))))) (. .)))
During the third week of embryonic growth the brain begins to develop in the early fetus in a process called induction.
(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.