I wondered whether the nuclear transfer techniques could be used to introduce purified macro-molecules into an egg, and hence into embryonic cells.
Within one year of starting work, I had found that the nucleus of an endoderm cell from an advanced tadpole was able to yield some normal development up to the nuclear transplant tadpole stage.
I left my frogs, which I had grown, with my supervisor, who had moved to Geneva, and he and a technician grew them up. So by 1962, they were adults, and one could publish a paper to say that these animals, derived from nuclear transfer, really were absolutely normal. So it took a little time to get through.
I must have been born with a strong attraction toward, and possibly even an aptitude for, doing things on a small scale.
As with most animal eggs, the early events of amphibian development are largely independent of the environment, and the processes leading to cell differentiation must involve a redistribution and interaction of constituents already present in the fertilized egg.
The aim of a nuclear-transplant experiment is to insert the nucleus of a specialized cell into an unfertilized egg whose nucleus has been removed.
