Limb regeneration in vertebrates: regulatory factors

Various regulatory factors are required in epimorphic regeneration of an adult newt limb. These factors (namely, amputational injury, the wound and apical epithelium, nerves (mitogenic agents), hormones (the hormonal milieu), bioelectric fields, probably the immune system, and possibly cyclic nucleotides and heretofore unknown regulators) act in concert and contribute to the developing microenvironment of the regenerate in support of normal regrowth and differentiation.