While fertility clinics have long paid for eggs, the voter-approved state ballot measure that created the $3 billion California Institute for Regenerative Medicine specifically bans compensating women for eggs donated for research.
Massachusetts, another center of U.S. stem cell research, also bans payments for eggs by law, and National Academy of Sciences guidelines advise against payments.
The restrictions are necessary, supporters say, to avoid creating a market for human eggs that encourages women to risk their health for speculative science.
But researchers argue that a shortage of eggs fueled by the payment ban is what's kept them from making the advances that prove their technique's real potential.
"You need to have enough eggs to make this thing work, and when you have enough eggs it does work," said Dr. Sam Wood, chief executive of La Jolla-based Stemagen Corp.
"If these guidelines...