( Unfortunately ( , ( ( the ( single-celled ( avian embryo ) ) ) ( ( ( is not ) ( readily accessible ) ) . ) ) ) )
(ROOT (S (ADVP (RB Unfortunately)) (, ,) (NP (DT the) (JJ single-celled) (NN avian) (NN embryo)) (VP (VBZ is) (RB not) (ADJP (RB readily) (JJ accessible))) (. .)))
Unfortunately, the single-celled avian embryo is not readily accessible.
(ROOT (S (NP (PRP We)) (ADVP (DT all)) (VP (VP (VBP start) (PP (IN as) (NP (DT a) (JJ single) (NN cell)))) (CC and) (VP (ADVP (RB soon)) (VBP grow) (PRT (RP into)) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN embryo)))) (. .)))