| Name: | presumptive atrium heart tube | 
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| Synonyms: | |
| Definition: | Multi-tissue structure that is part of the heart tube and will become the cardiac atrium. | 
| Ontology: | Anatomy Ontology [ZFA:0001718] | 
| Name: | anatomical region | 
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| Synonyms: | |
| Definition: | A 3D region in space without well-defined compartmental boundaries; for example, the dorsal region of an ectoderm. | 
| Ontology: | Spatial Ontology [BSPO:0000070] |