ABSTRACT
An essential component of most theories of pattern formation in epimorphic systems is that growth and pattern formation are strictly linked. Furthermore it has been assumed that epimorphic systems display size dependence, i.e. the pattern elements are always of a fixed size. These assumptions are challenged in the work described here on amphibian limb regeneration. The sizes of elements regenerating from small and large limbs and from normal and partially denervated limbs have been measured along with a detailed study of their subsequent growth stages. It is shown that the size of elements within one group of animals is remarkably constant even though their final, adult size is very different. But between groups of animals (large versus small or normal versus partially denervated) their sizes vary considerably. Therefore this classical epimorphic system is not size dependent, calling for a revision of current theoretical concepts. The similarities between this type of behaviour and that in morphallactic systems is discussed as well as similarities with growth control in limb development.
