Position specific binding of a monoclonal antibody in chick limb buds

To analyze the molecular mechanism of the limb pattern formation, we have tried to make monoclonal antibodies against antigens from chick limb buds. We obtained one antibody named AV-1 which recognized a specific region of chick limb buds. AV-1 reacted with the distal portion of the anteroventral mesoderm of only developmentally early chick limb buds. Grafts of ZPA region tissue to an anterior site in an embryonic chick wing bud resulted in mirror-image dupliction of the AV-1 antigen region. These data show the possibility that this antigen plays some role in the limb pattern formation. This is the first evidence that a position specific substance really exists in developmentally early limb buds in which the pattern has been considered to be unspecified.