Stem cells are cells that are able to differentiate into specialized cells. The cells in your organs are differentiated into a specific duty, i.e. your neurons carry electrical signals, your heart muscle cells contract, etc. The trick to building an organ is that you have multiple types of cells within it, organized in specific tissues with specific structures. Getting the stem cells to develop in such a way is a challenge.

Stem cell research is a very hot topic right now. There is a lot of stem cell research occurring right here at UC Santa Barbara.

Embryonic stem cells can be obtained without destroying the embryo. This involves tricky work removing a single cell called a blastomere from an early stage embryo. This can create human embryonic stem cells.

Removing single cells are already done to do genetics analyses on embryos. At an early enough stage the remaining cells can compensate for the loss of one.

Scientists are still learning how to use stem cells.They have done many experiments, but there are many more to do before we can develop organs from stem cells.

As I suspected, we can use stem cells to make the cell types of many different tissues. Organs have more than one type of tissue in them, and we're still a long way from being able to make organs in the lab. Our bodies are good at making organs, so I wonder if some day we'll be able to put stem cells into diseased organs in our bodies that will help the organs grow into healthy organs. For example, maybe we could find out how to put insulin-producing cells into the pancreas of a diabetic person, and the pancreas would be able to produce insulin. I'm guessing that there is already work on that.

Wikipedia says there are embryonic stem cells, from embryos, and fetal stem cells, from fetuses, as well as adult stem cells. I've read that stem cells can be removed from embryos without killing the embryo, but I'm sure the embryo would be endangered in the process.

There will be many questions to answer about whether an embryo is more important than a person, if the person would die without the stem cells from the embryo. It is exciting to read about new research on adult stem cells, because maybe our bodies have the cells we need to heal some diseased organs and tissues, without worrying about embryos and fetuses.