A fascinating bit of new science, as well as an important caution about doing science right. I suspect that these "oogonial stem cells" will change a lot of our understanding of reproductive biology, in much the same way that neurogenesis changed our understanding of brain biology.

h/t +Kee Hinckley for the link.
Eggs unlimited: an extraordinary tale of scientific discovery

This is not only a potentially landmark discovery, but also a cautionary tale about the dangers of seemingly well-established scientific dogma. In many ways, this is a classic example of the failures of the classical observationalist/inductivist form of scientific method, as opposed to empirical falsification, the approach put forth convincingly by Karl Popper, one of the greatest philosophers of science of the 20th century (http://en.wikipedia.org/wiki/Karl_Popper).

Instead of adhering so dogmatically to the view that eggs cells cannot be replenished in a woman's body, the scientific community should have welcomed continued attempts to falsify that view rather than viewing contradictory data with scorn and ridicule. As Popper noted, science does not prove the truth of hypotheses so much as it provides possible avenues and mechanisms for falsifying such hypotheses.

As this story shows, many members of the scientific community were as guilty as the Catholic church was against Galileo, and the albumen left on their faces in this case is doubly ironic in that the spheres in question were not planetary bodies, but rather egg cells. Perhaps the irony extends three-fold because the guilty party were respected scientists.

Eggs unlimited: an extraordinary tale of scientific discovery
Two biologists, split by rivalry and disagreement, suddenly realised that they were on the same side. The result was a revolutionary breakthrough.

A dogma has haunted the study and treatment of female infertility for more than half a century. It states that a baby girl is born with an ever-diminishing number of egg cells which cannot be renewed or replenished during her life, and that when she runs out of these eggs an irreversible menopause begins.

The dogma's origins go back to 1951 when Sir Solly Zuckerman, a South African born British scientist, published the definitive study showing “unequivocally” that the human ovary, like that of other mammals, has a finite resource of egg cells that begins to be lost during foetal development, even before a woman is born.

Estimates suggested that the female foetus has about 7 million putative egg cells that reduce to about 1 million at the point of birth. By the time of puberty, the teenage girl has between about 300,000 and 400,000 egg cells and these are lost at a rate of about 1,000 a month, with typically just one ripening to maturity at the time of ovulation.

[. . . .]

The problem with the dogma, and Zuckerman's “definitive” study, was that it turns out not to be true. In a series of remarkable studies published over the past eight years scientists have produced convincing evidence to suggest that women are not after all born with all the egg cells that they will ever possess.

Several research teams across the world have shown that the mammalian ovary is far more versatile than Zuckerman and his subsequent followers had ever thought possible. The core of this new thinking lies in the remarkable discovery of “oogonial stem cells” within the ovary that are capable of producing a constant supply of fresh eggs, or oocytes.

The discovery of these stem cells, which had gone unrecognised for six decades, has profound implications for the study and treatment of female fertility, as well as a plethora of other health conditions.

It raises the prospect of being able to grow unlimited numbers of human oocytes in the laboratory that could either be used in IVF treatment or as a source of embryonic stem cells to treat incurable illnesses such as Parkinson‘s disease.

But, even more profound, is the idea that human ovaries might be induced in some way to function well into old age, not for the sake of maintaining fertility but to retain the other health benefits that stem from active, egg-filled ovaries.

[. . . .]

It was Tilly's pioneering work in 2004 that kick-started the revolution now sweeping through fertility laboratories around the world. It was he who discovered and named the oogonial stem cells in the mammalian ovary.

Like so many important scientific discoveries, this one was unexpected and serendipitous. Tilly was working on a quite different problem when he and his team discovered something that they could not explain.

[. . . .]

The Edinburgh University team has already received material and expertise from Tilly and Dr Telfer is now about to apply for a licence from the Human Fertilisation and Embryology Authority (HFEA) to carry out the first fertilisation of a mature human egg derived from oogonial stem cells grown in a laboratory dish.

If an early human embryo is produced in this way it will dramatically alter the landscape for human fertility treatment. Women and girls undergoing ovary-destroying chemotherapy or radiation treatment may be able in the future to have their oogonial stem cells stored and banked so that they could later have an unlimited supply of their own eggs for IVF treatment.

#science #biology #longevity #ScienceSunday
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