At the risk of repeating what has been discussed several times here, I start:
ES cells for therapy has a long way to go and we know it (evident from all the ongoing disucssions). ES resarch provides a great opportunity to understand the basic developmental processes, facilitating, much needed ground work for future therapies. It may be neurons for PD or a heart or a pancreas for a patient who needs it.

Going back to the questions and concerns expressed here I have a few answers:
Chromosomal abnormalities and the associated developmental problems increase as cells divide and so early stage blastocytes will likely to be free of chromosomal abnormalities. I dont know if fertility clinics do a chromosomal spread for thier clients, but if they do that would be valuable. I do agree we cannot say that the blastocytes are "normal". How do you define normal when each is unique?

If you look into Pubmed, you notice that molecular, cellular and developmental biologists have developed very sophisticated and sensitive methods (not my field to go into details) to moniter the development and differentiation of embryonic cells in worms, flies and zebra fish. From what I understand, the lineage and the fate of every single cell in an embryo of C.elegans (worm) has been monitored and deciphered by scientists. I would imagine all that info will be utilized to understand human cell differentiation.

Also, these ES cells from the fertility clinics are going to be used to generate mostly one kind of cells or tissue at this point and not a multi-cellular organ with various cell types. ES cell growth and differentiation are tailored to one's requirements by controlling the growth factors added to the cultures. Most important thing for me is how to stop the growth and differentiation of these cells and make them stay where they are placed and needed.

I know scientists havent tried hard enough to connect outside of thier community, Please have faith in them and in the system. Most scientists are honest, ethical, dedicated to their work, put heart and soul into what they do..Most prefer to be left alone to do their work, I guess thats the problem! NIH has the world best brain power you can imagine (well, in biology!) and NIH is open, collaborative and tries to fund good grants. Clearly, they do a good job but could do better! The issues discussed in this forum are wonderful and thought provoking/ Keeps my brain cells (whatever is left in there!) active and THANKS for that!

Girija