has part has part has_part characteristic of part of has modifier blastocyst hatching abnormal blastocyst hatching delayed blastocyst hatching from the zona pellucida the hatching of the cellular blastocyst from the zona pellucida, the thick solid transparent outer membrane that surrounds the developing ovum and embryo prior to implantation, occurs later in development than expected MP:0003695 MPheno.ontology abnormal delayed