[claytonius]

Oocytes are one of the most difficult cells to engineer as well... The mitochondria in Oocytes are turned off from birth because otherwise reactive oxygen species will damage the mtDNA. One would have to use CRISPR to re-build the mtDNA, use telomerase / crispr to get the telomeres to exactly the right length, fix any mutations within the genome, etc. There are many many technical challenges to overcome, requiring further development of multiple immature technology stacks, and the bar is much higher than it is for mice since you would want a baby with the cellular metabolism profile of a 30y/old.