... biology both influenced and benefitted from this process. Developmental biology IVF Embryo transfer In vitro fertilisation (IVF; Fig. 1 ) is defined as the fertilisation of an egg by a spermatozoon outside the body. Because many organisms routinely fertilise their eggs in this way...

... of injection into enucleated oocytes, and that these reconstructed SCNT embryos can result in implantation and pregnancy after transfer into recipient hosts. Nuclear formation, normal division of SCNT embryos and pregnancy after SCNT-embryo transfer were not markedly affected by the donor cell, as they were...

...) controls - the natural offspring of timed matings, (2) transferred controls - offspring from 2-cell embryos transferred to recipients 1 day asynchronous, and (3) transferred half embryos - offspring developing from one blastomere from the 2-cell stage transferred to recipients 1 day asynchronous...

... and maternal contribution has not previously been determined. Using embryo transfer and reconstituted blastocyst techniques, combined with isozymal and in situ genetic markers, we have established that about 70% of the 13 to 15-day placenta is trophectoderm-derived, 30% is maternal in origin, and 4% develops...