Bones, feathers, teeth and coat marking: a unified model

Abstract

The formation of structure within the developing embryo is perhaps the most important and remarkable phenomenon in science. From the almost uniform mass of dividing cells in the very early stage of development, emerges the vast range of pattern and structure observed in animals. The skin, for example, forms many specialised structures such as hair, scales, feathers and glands, as well as antlers andhorns. Butterfly wings exhibit spectacular colours and patterns and many animals develop dramatic coat markings.
Although genes play a key role, genetics says nothing about the actual mechanisms which produce pattern and structure as an organism develops from egg to embryo to adult form - knowing the dictionary does not mean that we know Shakespeare. The development of structure and form is called morphogenesis and consists of a complex interaction of mechanisms. In spite of a vast amount of research the mechanisms involved are still not fully known and are the source of intense interest and controversy amongst experimentalists and theoreticians.