Table 2.04 - Summary of Developmental Events in the Cardiovascular System. See Time of Occurrence of Normal Events, A. & B.
| Ovulation age [in days] | Approximate size | Event |
|---|---|---|
| 18 | presomite | angiogenic tissue appears, vitelline vessels appear |
| 19 - 20 | 1 - 2 somites | appearance of endothelial heart tube, umbilical veins appear
|
| 21 | 4 - somites | fusion of endothelial heart tube |
| 21-22 | 6 somites | differentiation of atria, ventricle and bulbus cordis |
| 25 | 14 - 16 somites | fusion of primitive atria, formation of bulboventricular loop |
| 26 - 27 | 20 somites to 10 mm | Pharyngeal arch arteries appear |
| 28 | 26 somites | arterior cardinal veins appear |
| 29 | 3.5 mm | posterior cardinal veins appear |
| 32 | 5 mm | septum primum appears |
| 33 | 6 mm | interventricular septum appears |
| 33 - 34 | 6 - 7 mm | right umbilical vein disappears |
| 35 | 8 mm | foramen secundum present |
| 36 - 37 | 9 - 10 mm | atrial cushions fuse |
| 43 | 15 mm | bulbar ridges fuse |
| 46 | 17 mm | interventricular foramen closed |
| 47 | 18 mm | septum secundum appears |