| Name: | ball | 
|---|---|
| Synonyms: | yolk ball | 
| Definition: | The anterior round region of the yolk cell present after the yolk extension forms during the segmentation period. | 
| Ontology: | Anatomy Ontology [ZFA:0000006] | 
| Name: | vH ionocyte | 
|---|---|
| Synonyms: | HR cell, VH-MRC | 
| Definition: | Integument ionocyte rich in vacuolar-type H+ ATPase and carbonic anhydrase. | 
| Ontology: | Anatomy Ontology [ZFA:0005327] |