The National Institutes of Health laboratory in Montana made “humanized mice” by implanting the mice with tissues cut from human livers and thymuses taken from babies at 17 to 22 weeks gestational age.  The production of TKO-BLT mice to obtain healthy mice with high level reconstitution of human cells and tissues requires specialized methods that are presented in detail. The part of the liver not cut into small pieces and transplanted under the kidney capsules of mice was cut into small pieces and processed to make stem cells that were injected into the mice after they underwent their transplantation surgeries.

Questions regarding the origin of the tissues from CNSNews.com included inquiries about the minimum and maximum gestational ages a baby needed to be in order to donate a liver and thymus usable for transplantation into the mouse, and whether any of the organs used came from babies who died from miscarriages rather than from abortions. Most answers have gone unanswered.