In the alternative, scientists could edit a newly conceived Asian elephant zygote directly. Either way ... of the animal tree ...

Identical twins arise from a single fertilized egg, or zygote, splitting into embryos with duplicate DNA, but what causes the split remains unknown. Zygote splitting was once thought ...

Here's why. Identical twins (also called monozygotic or MZ twins) are conceived when a single sperm fertilizes a single egg and the resulting zygote divides in two. Because the zygote originated ...

The zygote inherits two fully active X chromosomes and begins re-inactivation of the paternal X chromosome (XP) at the 4- to 8-cell stage. In the trophectoderm (extra-embryonic cells, shown in ...