( Blastocyst ( Stage ( Embryo Transfer ) ) )
(ROOT (NP (NNP Blastocyst) (NNP Stage) (NNP Embryo) (NNP Transfer)))
Blastocyst Stage Embryo Transfer
(ROOT (S (PP (IN After) (NP (NN implantation))) (, ,) (NP (DT the) (NN blastocyst)) (VP (VBZ is) (VP (VBN called) (NP (DT an) (NN embryo)))) (. .)))