Stem Cells are the building blocks of a person, they come from blastocysts (a blastocyst is what happens when the sperm and egg come together and start multiplying). This type of stem cell can become anything in the body because it hasn't been pre-programmed yet to become something else. The problem with adult stem cells is that they've already been pre-programmed. (eg. take stem cells from bone marrow) They've already been assigned a task so it's difficult to get it to do anything else, which is why embryonic stem cells are preferred in stem cell research.
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A termination would have to occur very early for 'abortion for stem cells' to occur because blastocysts only occur about the 4th of 5th day of a pregnancy. After that it's already 'programmed' to do something in the body, at least as far as I understand. It's been a while since I took a bio course so I could be wrong about this section.
The embryonic HAS to be from an aborted fetus? No. People who are going through IVF often produce more eggs that have been fertilized (blastocysts) than what they're going to use themselves. I believe they have the option of donating them to other couples or discarding them. Instead of discarding them they want to use them for research with the parents consent.
Not sure about cord cells though. Why is this stuff potentially helpful? Because if we can manipulate the 'building blocks of life' then things like MS, Parkinsons, etc. can be helped. Lungs can theoretically be grown, etc. Of course all of this stuff is theoretical right now.
Federally funded stem cell research has been banned but private research hasn't.
I think this has gotten some of your questions..