Originally Posted by
MistressNomad
It's kind of a long answer, but basically, a mass connected to a living organism typically does not have any blood vessels at all, unless it is a very advanced cystadenoma, or cancerous. Fortunately for me it was not cancer. And no, such a structure can't sustain itself without a pump. Interestingly, my cyst also had a bifurcation, which aids in division of labor in keeping it alive, and other such structures - just like a heart has. It did have organs of sorts, actually. Even individual cells have organs.
But neither can the heart of a zygote or fetus sustain itself because it doesn't have the other systems in place which make it self-sustaining, such a developed automated neuronal system (also why they don't feel pain, think, etc), or ability to process nutrients or protein.
Even a parasite has better self-sustaining capability than a fetus or zygote.
Also, what about fetuses and zygotes not yet that developed? A fetus doesn't have a functioning heart at all until over a month into gestation. A large minority (somewhere around 30% - an exact number is hard to find) of abortions take place at or before that point.
So are those abortions ok?