what would happen if a human egg and sperm were combined and then implanted into a different animal?

miscarriage..............................................................!

Try these scenarios:

o The mom and zygote die.  Attempting to implant a human zygote into a marine copepod or a beetle isn't going to do anyone any good.

o The zygote dies.  Most animals aren't equipped to handle a human zygote in any useful way.

o So you confine your experimentation to placental mammals.  The most likely result is that the embryo doesn't properly implant into the uterus, because it doesn't recognize the uterus of your foster mom as being a uterus.

o Your baboons, mandrills, macaques experience an early miscarriage.  That's probably a good thing, since they're not big enough to carry a human fetus to full term.

o Your gibbons also miscarried.  You're not sure why.  Your autopsy of the fetus indicates head injury trauma.  Human fetuses just aren't tough enough for an arboreal brachiator existence.

o Your orang-utans, gorillas, and chimps miscarried too.  You suspect that the uterine hormone interaction is subtly different from a human's.

o Your Neanderthals and Denisovans and a couple of other big-headed hominin species gave birth to a healthy human baby.  Interpol catches up with you and you spend the rest of your life in a prison.

It would die.    

The combination would be attacked by the anti-bodies in the animal, which would destroy it. Even if that did not happen, the egg would not get the right nutrients, and would quickly die from that.

The fertilized egg would quickly break down and become inert.