If the procedure can be repeated in humans the technique could make it easier for women in their 30s or 40s to have children and could help men and women whose reproductive organs have been damaged by cancer treatments or other causes.
"These studies provide that next level of evidence that in the future fertility could be managed with stem cell intervention," Teresa Woodruff, chief of fertility preservation at Northwestern University's Feinberg School of Medicine, told the Los Angeles Times.
Using stem cells to grow new eggs is particularly important since women are born with a set number and don't make more once they are gone.
The stem cell technique would in effect allow them to turn back their biological clocks, Stanford stem cell researcher Renee A. Reijo Pera said.
"This is a get-them-back strategy," she said.
About 10 percent of American women of childbearing age have trouble becoming or staying pregnant, and more than one-third of infertile couples are dealing with a medical problem in the prospective father, the national Centers for Disease Control and Prevention in Atlanta said.
Dr. Mitinori Saitou and colleagues at Kyoto University detailed how they generated the functional mouse eggs in the journal Science and the same researchers reported doing the same thing with mouse sperm last year.