41. Four embryonic stem cell lines from human fetal somatic cells were derived from those blastocysts . 42. Monozygotic twinning is not increased after blastocyst transfer compared with cleavage-stage embryo transfer. 43. Pre-implantation blastocyst development is a controlled cascade of gene regulation and intercellular signaling. 44. One cell type endures the knockout and is put into a blastocyst of another type. 45. WWC2 expression is found to be elevated in the blastocyst and fetal stages of development. 46. The blastocyst is then implanted in the mother's uterus and the pregnancy proceeds normally. 47. Because the cells grow and divide indefinitely in culture, very few blastocysts would be needed. 48. Before leaving Worcester, I ask Cibelli when he will know if any blastocysts have formed. 49. Sixteen blastocysts survived the biopsy ( the removal of one or two cells for screening ). 50. That means that in principle the cells from just a single blastocyst could satisfy all requirements.
