Morphologies and development of blastocysts in culture. Morphologies of blastocysts showing normal (A) or degenerated appearance (B) under phase contrast microscope. Note that blastocyst in A is undergoing zona pellucida (ZP) hatching. Normal inner cell mass (ICM) and trophoblast outgrowing (C) scored as +++, when compared with reduced tissue outgrowing (D) occurring in composite-conditioned medium and scored as ++. Magnification approximately 200 × (A, B) and 100 × (C, D).