Monday’s Google Doodle celebrates the 94th birthday of biologist Anne McClaren, who discovered a way to grow mammal embryos in lab cultures. Her work, published in 1958, laid the foundation for in-vitro fertilization 20 years later, along with new research techniques.
Today, most medical and biological research that eventually impacts humans begins with mice. At a basic level, most mammals are similar enough that scientists can use mice as “models” for how drugs, genes, or diseases might work in humans. There’s even a statue honoring laboratory mice in front of the Russian Academy of Sciences’ Institute of Cytology and Genetics in Novosibirsk, Sibera. The bronze statue features an elderly, bespectacled mouse knitting a DNA molecule.
Fittingly, Anne McClaren’s scientific career also started with mice, in a way. If you look up H.G. Wells’ 1936 science fiction movie The Shape of Things to Come, you can see a 9-year-old McClaren listening to her on-screen great-grandfather explaining the dazzling accomplishments of human spaceflight in 2054: in Wells’ and McClaren’s fictional future, mice had just landed on the Moon.
Years later, with a zoology degree from Oxford University, McClaren came back to mice. She spent the 1950s studying how mammal embryos develop, using mice as a model. McClaren and her colleague John Biggers figured out how to combine a mouse egg and sperm in in a petri dish in order to grow mouse embryos in a lab culture instead of inside a mouse.
That paved the way for a huge part of the way modern research on mice, and other animal models, gets done. Scientists can study an embryo growing in a petri dish in much more detail than one growing in a mouse uterus, and they can also more easily select embryos for the specific traits or genes they want to study.
McClaren’s work also laid the basic foundation for in vitro fertilization (IVF), the procedure that fertility clinics use to grow human embryos in a medical lab and then implant the embryo into the mother’s uterus.
It took about 20 years for other researchers, using McClaren and Biggers’ technique as a starting point, to develop the rest of the knowledge and technologies required to make IVF work, but in July 1978 a British woman named Lesley Brown gave birth to a daughter named Louise. Louise had been conceived in a petri dish in the lab of physiologist Robert Edwards, whose team implanted the embryo in Lesley Brown’s uterus shortly thereafter.
About two months later, a mother in India gave birth to a daughter named Durga, who had been conceived the same way in the lab of Dr. Subash Mukhopadhyay. While Edwards later received a 2010 Nobel Prize in Physiology and Medicine for his work, Mukhopadhyay – who developed his IVF method independently – did not. Arguments about who gets credit for a particular discovery or invention can get heated and often come down to hair-splitting technicalities, but it’s also worth mentioning that the nomination process for the Nobel Prize has been historically skewed toward white, male scientists.
About 8 million children have been born worldwide thanks to IVF, as of a 2018 estimate. Louise Brown’s younger sister Natalie was number 40, about 4 years after Louise’s birth made history. While humans aren’t the only beneficiaries of IVF, we’re definitely the most ethically fraught.
When prospective parents visit a fertility clinic for IVF treatment, the clinic retrieves enough eggs and sperm to create several embryos, and only a few of those will end up in the hopeful mother’s (or surrogate’s) uterus. Most of the ethical questions surrounding IVF boil down to two things: how should parents and doctors choose which embryos to implant, and what should they do with the others?
For example, should parents rummage through the available embryos to choose a male or female? Should in vitro embryos with genetic disorders be implanted or ruled out? That question cuts both ways; eugenics is clearly bad, and medical ethicists generally prefer to give that particular slippery slope a wide berth. In the 1990s a deaf couple wanted to select an embryo for future deafness, which raised new ethical questions.
And once those choices have been navigated, what becomes of the extra embryos? In most places, parents and their doctors can choose to freeze the embryos for later use, donate them to other hopeful IVF parents, allow them to thaw – thus making them unviable – or donate them to research. Embryos used for medical research can help scientists understand the earliest stages of development, and they also enable potentially lifesaving stem cell research.
The ethical implications of those choices, for individual parents, often depend on their personal beliefs about when a fertilized egg becomes a person. At the stages of development involved in IVF (usually 5 to 10 days) and embryonic research (never more than 14 days), that’s a philosophical or religious question, not a scientific one.
McLaren herself helped create that 14-day rule. For 8 years, starting in 1982, she served on the UK committee that helped draft that country’s IVF regulations in 1990. The following year, she became the first woman to hold office in the Royal Society, which named her its foreign secretary in 1991 and later its vice president.