AbstractChicken eggs of 4 or 6 days of incubation were injected with 10 μg 6‐aminonicotinamide (6‐AN) or 6‐AN plus various doses of sodium ascorbate, calcium ascorbate, or ascorbic acid; 11‐day embryos were examined grossly and histologically. 6‐AN‐treated embryos had various degrees of micromelia and were reduced in overall size. All three ascorbates inhibited 6‐AN teratogenesis but not completely. The extent of inhibition was dose related. Increased amounts of intercellular matrix and decreased necrosis of chondrocytes in the limb cartilage of protected embryos correlated with the