Stem cells...?

Question

Hi!

What makes a stem cell pluripotent? Is it just the fact that it was taken from an already differentiated cell and it cannot be reversed?

Is it not possible for a stem cell to produce, say, an oocyte, so that really, it's totipotent? (Because a fertilized egg is the ultimate totipotent cell)

Or am I taking this too far... like, is the difference b/w toti- & pluripotency only *relatively* short term?

Thanks!

Answer 1

I Have had the Same Problem, to me, Pluripotent Means it has Already Gone Down the Road of Differentiating, and Can Give Rise to Specific Tissues, Stem, All Tissues.

Answer 2

Cells cannot regress to earlier forms. There is a programmed age within each cell, it is not fully understood, but it is recognised. Cloning experiments with Dolly the sheep showed that, at the present time, there is no way to get around cell age. It would be a remarkable breakthrough if we could reverse cell development, because we would then not need to kill foetuses for stem cell research. The researcher could just regress his/her own cells, and start with a pluripotent stem cell.
Or, go right back and create an oocyte from a mature cell. That would raise a few issues about creating life and playing God.