> The eggs from both the mother and the donor are fertilised in the lab with the dad's sperm.
The article seems clear. Another comment [1] suggested it should be possible to do as you suggested but I certainly do not know the science in this space.
The article uses the colloquial definition of fertilization, i.e. that fertilization is a moment, specifically the moment the sperm enters the egg. In literature, fertilization is a ~24 hour long process instead, which kicks off when sperm meets egg, and finishes when a zygote is successfully created [0] inside. The sperm entering the egg is relatively early on during that.
The article further refers to "donor" and "parent" embryos. This is also not correct as far as I undestand, eggs turn embryos once the fertilization process completes, and a zygote is present. [1] Even this could be considered misleading as there's also an "embryo proper" which forms about a week later still, but I wanted to keep to the reference frame of the GP.
That's very interesting, thank you for the context. I imagine I learned some amount of this long ago and have lost it to disuse. I also think I agree with the majority of your analysis after reading your references as well as [1] and [2]. And I apologize for my uninformed quoting of a line from the article and appreciate the education.
I found [2] particularly informative because it outlines a multi-stage process through which an embryo goes, the earliest of which is fertilization as you described. My reading in the article, and perhaps relying too much on the artwork, seems to put the process described there at stage 1b-1c since the pronuclei looks to be in the process of fusing. My conclusion in cross-referencing [1] is that your "embryo proper" is around stage 4-5 and would have been implanted?
> They're removing the pro-nuclei before they fuse (which is when a new human, specifically their first sovereign cell and their DNA, would be formed).
I wish I'd had the context to appreciate this before my earlier reply. :)
I also enjoyed reading parts of [3] and imagine there is probably better information nearly 60 years later.
> My conclusion in cross-referencing [1] is that your "embryo proper" is around stage 4-5 and would have been implanted?
No, I believe what happened is that they made their mitochondrial changes before the pronuclei fusion, and inserted this modified egg into the womb. There it the continued on with the fertilization process, finishing up, creating the zygote, etc.
The embryo-proper bit was only relevant to the "from what point is it a human life" part of this, it is not relevant to the procedure specifically. That comes a whole week after fertilization I believe.
The article seems clear. Another comment [1] suggested it should be possible to do as you suggested but I certainly do not know the science in this space.
[1] https://news.ycombinator.com/item?id=44617740
> The spindle transfer method transplants the mother's egg's DNA into the donor's egg before fertilization