-A living embryo would never be in a petri dish. Zygotes can be created in the lab, but at our current level of scientific ability, a zygote must be implanted in a woman in order to develop into a embryo.
-What you are describing is an emotional response, not a reasoned one. People get more upset by the death of dogs in movies than the death of humans.
-Just for the record, I am not firmly anti-abortion, but I believe if woman is certain that she doesn't want to go through a pregnancy, she has on obligation to make that decision as early as possible. (I am firmly anti late term abortion)