In a first, scientists have nurtured human eggs to maturity in a laboratory.
Evelyn Telfer and her colleagues at the University of Edinburgh were able to bring 10% of immature eggs into maturity by careful controlling environmental conditions like oxygen levels, hormones, growth protein, and where the eggs were cultured. None of the eggs were fertilized, so Tefler doesn’t know if they’re viable.
While a lot of work still needs to be done, the research brings hope to girls undergoing cancer treatment. Sterility is an unfortunate side-effect of chemotherapy and radiation treatments, and this gives young girls—whose eggs haven’t matured—the possibility of bearing children when they’re older.
How human eggs develop is still a scientific mystery, but this research improves our understanding. Here’s James Gallagher for BBC News:
The process is very tightly controlled and timed in the human body—some eggs will mature during the teenage years, others more than two decades later. An egg needs to lose half its genetic material during development, otherwise there would be too much DNA when it was fertilized by a sperm. This excess is cast off into a miniature cell called a polar body, but in the study the polar bodies were abnormally large. “This is a concern,” said Prof Telfer. But it is one she thinks can be addressed by improving the technology.
Currently, the best hope for girls with cancer is to have a portion of their ovaries frozen and then re-implanted later, though the procedure is risky.
Tefler pointed out that the lab-matured eggs have at least one glaring abnormality at this point—their polar bodies, which contain chromosomes shed during egg development to reach the required 23, are unusually large.
The team hopes to study the eggs and the process further, including attempting to fertilize one to prove its viability. In the United Kingdom, it’s legal to fertilize one of the lab-made eggs to create an embryo for research purposes, though only after the eggs have been tested for chromosomal and other abnormalities.