( ( Primary oocytes ) ( ( begin ( ( ( ( ( meiosis I ) ( in ( the embryo ) ) ) , ) but ) ( ( do not ) ( ( ( complete it ) ( until ovulation ) ) ( to ( ( give rise ) ( to ( ( ( one ( secondary oocyte ) ) and ) ( a ( polar body ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Primary) (NNS oocytes)) (VP (VBP begin) (SBAR (S (VP (VP (VBZ meiosis) (NP (PRP I)) (PP (IN in) (NP (DT the) (NN embryo)))) (, ,) (CC but) (VP (VBP do) (RB not) (VP (VB complete) (NP (PRP it)) (PP (IN until) (NP (NN ovulation))) (S (VP (TO to) (VP (VB give) (NP (NN rise)) (PP (TO to) (NP (NP (CD one) (JJ secondary) (NN oocyte)) (CC and) (NP (DT a) (JJ polar) (NN body))))))))))))) (. .)))
Primary oocytes begin meiosis I in the embryo, but do not complete it until ovulation to give rise to one secondary oocyte and a polar body.
(ROOT (S (NP (NP (DT The) (NN cell)) (VP (VBG starting) (NP (NNS meiosis)))) (VP (VBZ is) (VP (VBN called) (NP (DT a) (JJ primary) (NN oocyte)))) (. .)))