A structured controlled vocabulary of stage-specific anatomical structures of the human. It has been designed to mesh with the mouse anatomy and incorporates each Carnegie stage of development (CS1-20). The abstract version of the human developmental anatomy ontology compresses all the tissues present over Carnegie stages 1-20 into a single hierarchy. The heart, for example, is present from Carnegie Stage 9 onwards and is thus represented by 12 EHDA IDs (one for each stage). In the abstract mouse, it has a single ID so that the abstract term given as just heart really means heart (CS 9-20). Timing details will be added to the abstract version of the ontology in a future release.