MULTIPLE DIGIT FORMATION IN XENOPUS LIMB BUD RECOMBINANTS

We prepared recombinant limb buds of Xenopus tadpoles by grafting a me senchyme mass of the hindlimb bud. The Xenopus recombinant limb buds w ith dissociated and reaggregated mesenchyme developed more than 30 dig its with cartilage segmentation, while those with undissociated mesenc hyme developed a limb with normal cartilage pattern. Before the format ion of multiple digits, a patchy expression pattern of fgf-8, an AER m arker, was observed in the distal region of recombinant limb buds. shh , a ZPA (zone of polarizing activity) marker, was expressed broadly in the distal region of recombinants. Recombinant limb buds with the rea ggregated mesenchyme of anterior halves formed anterior digits with cl aws, and those with the mesenchyme of posterior halves formed posterio r digits without claws. The temporal and spatial changes in the potenc y of multiple digit formation are discussed with reference to the rege nerative capacity of Xenopus limb buds. (C) 1998 Academic Press.