"On February 29, 1980 (enough of a rarity in itself), E.J. Kollar and C. Fisher reported an ingenious technique for coaxing chickens to reveal some surprising g

"On February 29, 1980 (enough of a rarity in itself), E.J. Kollar and C. Fisher reported an ingenious technique for coaxing chickens to reveal some surprising genetic flexibility retained from a distant past." -- Stephen Jay Gould, Hen's Teeth and Horse's Toes Two pages of technical explanation follow, but they got chicken embryo tissue to produce teeth.