[An experimental study on the pathogenesis of congenital hand malformations--with reference to local disturbance in...

Pathogenetic conditions for polydactyly and its pathogenesis were studied by inducing the condition at a high incidence by incubating fertilized ova of white leghorns and locally cauterizing the limb bud with a bipolar microcoagulator. Polydactyly commonly occurred in about 12 hours of the latter half of the third day after cauterization (5 watts) of the preaxial area of the limb bud. This suggests the involvement of space- and time-specificity under the appropriate strength of such stimulation in the pathogenesis of polydactyly. Most polydactyly involved the first toe. Disturbance in the primordium of the metatarsal bone was believed to be related to the pathogenesis. Many reductive complex malformations resembling polydactyly were seen, and the repairing mechanism of these malformations was similar to that of polydactyly. Thus, it seems that the repairing mechanism is oriented to acquiring the proper number of toes and that acquisition of the first toe becomes particularly dominant, resulting in a tendency for polydactyly in the first toe.