Table 1.
Evidence for and against inversion: The dorsoventral location of anatomical elements and gene expression domains in protostomes, hemichordates, and chordates
| Anatomical element/gene | Location of
element and associated gene expression
|
||
|---|---|---|---|
| Protostomes | Hemichordates | Chordates | |
| Mouth | Ventral | Ventral | Ventral |
| Nerve cord | Ventral | Dorsal (hollow) | Dorsal (hollow) |
| Ventral (solid) | |||
| Neural genes | vnd/ind/msh, netrin | ?? | Nkx2/Gsh/Msx, Netrin |
| sog/chordin domain | Ventrolateral | ?? | Dorsal |
| dpp/bmp domain | Dorsal | ?? | Ventrolateral |
| Heart | Dorsal | Anterior, dorsal | Ventral |
| Heart genes | tinman | ?? | Csx/Nkx2-5 |
| Notochord | Absent | Dorsal stomacord | Dorsal notochord |
| Ventral pygocord | |||
| Post-anal tail | Absent | Posterior, ventral to anus | Posterior, dorsal to anus |
| Liver | Absent | Dorsal | Ventral |
| Endostyle | Absent | Dorsal? ventral? | Ventral |
| Gill slits | Absent | Lateral | Ventrolateral |
| Left-right asymmetry | Absent? | Left pore of anterior coelom | Left dominant Nodal, Shh, Pitx |