Placenta may be a source for human eggs

Replicating the egg-making recipe

Amniotic membrane cells arise about eight days after conception. Their job is to preserve the plasticity of an embryo’s cells before they differentiate. Evron and Shalev found that these cells also have the ability to differentiate into ones that express the properties of the germ cells that produce eggs in a woman’s ovaries.

Ordinarily, the germ cells remain undifferentiated until a female reaches puberty because they cannot turn into eggs without the action of proteins or hormones that begin to surround the ovaries of girls in adolescence. The researchers, who published their work last month in the journal Reproductive Biology and Endocrinology, are now attempting to replicate the conditions present in adolescents. Theoretically, they could produce human eggs by adding the right recipe of proteins or hormones to the differentiated amniotic cells.

“Germ cell development has been difficult to study in humans because important early events occur after implantation [of the fertilized egg],” said Shalev. In addition, the study of germ cell development in humans is challenging because ethical issues can be involved in harvesting these cells. He stressed that though they have discovered the principle behind this advance in human reproduction, “it is too early to know when this will be achieved.”

But if the principle can someday be put into practice successfully, he added, “women who do not produce healthy ova — or any at all — could use them to become pregnant.”

By Abigail Klein Leichman