No. 24: Nov-Dec 1982
Anomaly 2. Foretoe regeneration in mice is astoundingly sensitive to the site of amputation. Move the site only 0.2 0.3 millimeters farther back and no regrowth will occur. No one understands why such a tiny change in distance completely changes the body's response.
(Borgens, Richard B.; "Mice Regrow the Tips of Their Foretoes," Science, 217:747, 1982.)