( ( Cleavage ( of ( ( ( just ( the embryo ) ) and ) ( not ( the ( yolk sac ) ) ) ) ) ) . )
(ROOT (NP (NP (NNP Cleavage)) (PP (IN of) (NP (NP (RB just) (DT the) (NN embryo)) (CC and) (NP (RB not) (DT the) (NN yolk) (NN sac)))) (. .)))
Cleavage of just the embryo and not the yolk sac.
(ROOT (S (NP (NP (DT The) (JJ amniotic) (NN sac)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBD was) (VP (VBG sitting) (PP (IN on) (NP (NP (NN top)) (PP (IN of) (NP (DT the) (JJ flat) (NN embryo))))))))) (, ,)) (VP (VBZ envelops) (NP (DT the) (NN embryo)) (SBAR (IN as) (S (NP (PRP it)) (VP (VBZ folds))))) (. .)))