Definition: "Organ that is a component of the central nervous system and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. It appears when the neural tube segregates in forebrain, midbrain, and hindbrain at NF stage 22. The general pattern of the brain has been mainly established at NF stage 28. Yolky material is consumed and the fibre tracts and later the commissures develop. In general all of its parts are well developed at NF stage 53 and later development consists mainly of growth and some further cytological differentiation. In the period of metamorphosis only topographical changes take place."