Development. The science of damage limitation.

The building of a normal embryo is not accomplished by following a series of complex instructions; rather a number of critical processes enable the cells involved in the process of development to follow pathways which subsequently constrain their growth, mobility and differentiation. There is considerable redundancy in the system, both in terms of mechanisms and permissible outcomes. The way that these processes have become established in evolution gives us a number of insights into how these processes may fail and information from developmental biology informs us about a number of other pathological processes.