The different growth zones of the fetal foot.

Previous publications revealed no reliable data or models concerning the three-dimensional ontogenesis of the lower extremity. Using the method of plastination-histology in combination with 3D-computer-reconstructions we were able to produce exact, virtual 3D-specimens of 19 healthy fetal feet. The fetuses were aged between 9 to 38 weeks of gestation and age-dependently related to four defined age-groups. We compared these feet with the help of a new geometrical method. Thus, we obtained a kind of "slow-motion-picture" of the undisturbed three-dimensional development of the fetal foot. Our results show that the human fetal foot has a desultory mode of growth and that growth priorities within the foot-skeleton change dependent upon age and region. Though the growth of the fetal foot-skeleton is desultory, it is not disconnected. The result of this peculiar mode of growth is to create the foot arches and thus seems to be functionally-oriented toward the human foot's specific purposes.