Assertion: embryo | /r/Synonym | pre-implantation embryo
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: At the blastocyst stage, five to 10 days after fertilization, the embryo is a cluster of 100-200 cells (it is sometimes called a pre-implantation embryo because in a pregnancy, a blastocyst has not yet implanted in the uterus).