Textual annotations using controlled vocabularies. (a) General categories of anatomical terms and the developmental relationships between them. We distinguish four types of anatomical structures: 'anlage in statu nascendi', 'anlage', 'primordium' and differentiated 'organs'. Below each heading are examples of staining patterns that illustrate a specific instance of that category of developmental structure. The examples are not developmentally related. Anlage in statu nascendi, anlage and primordium become suffixes to the specific name of a structure, such as dorsal ectoderm anlage in statu nascendi, head mesoderm anlage and Malpighian tubule primordium. Differentiated organs are named without a suffix, for example fat body. (b) Embryos at the indicated stages stained with a probe for the gene single minded reveal the developmental origin of the midline glia. Ventral view, anterior to the left.