Alfred Jost's rabbit experiment: how did he actually do it?
Check out Fig. 7 in the document at http://ipubli-inserm.inist.fr/bitstream/handle/10608/4343/MS_1991_3_263.pdf . The caption says: "Castration of a 23 day fetus. [Mother's] womb is open, the rear end of the fetus is pulled out, a flank incision is performed, and the testicle, located on the mesonephros, is exposed, then cut. After bilateral testicular removal, the fetus is re-placed in the womb. [..] For ease of explanation, an older fetus is in fact shown."