1. 3
2
1 – Head Process
2 – Head Fold
1 3 – Proamnion
5 4 – Area Opaca
4 5 – Area Pellucida
6 – Primitive Plate
6

2. Hensen’s Node
Primitive Pit
Primitive Groove
Primitive Ridge
Area Pellucida

3. 5
3 1
2
4
1 – Neural plate
2 – Notochord
3 – Epiblast
4 – Hypoblast
5 – Yolk darkly stained cells are Blood Islands

4. 3 1
4
2
1 – Hensen’s Node
2 – Blood Islands
3 – Epiblast
4 – Hypoblast

5. 1
3
4
2
1 – Primitive Pit
2 – Primitive Knot
3 – Epiblast
4 – Hypoblast

6. 2
1
Primitive Gut
1 – Primitive Groove
2 – Primitive Ridge

7. Anterior Neuropore
Neural Groove
Neural Fold
Head fold
Somites
Unsegmented Mesoderm
Blood islands
Hensen’s Node

8. 1 – Anterior Neuropore
2 – Head Fold
3 – Neural Groove
Neural Tube
4 – Neural Fold
5 – Somites
6 – Primitive Streak
7 – Area Pellucida
8 – Hensen’s Node
9 – Unsegmented Mesoderm
9
8

9. 1 – Blood Islands
7 6
2 – Thickened Splanchnic Mesoderm
3 – Intersomitic Grooves
4 – Notochord
8 5 – Margin of the Anterior Intestinal
Portal
6 – Head Fold
7 – Margin of the Foregut
5 8 – Anterior Intestinal Portal

10. Anterior neuropore
Head Mesenchyme
Neural folds
Subcephalic pocket
Neural groove
Pharynx
Oral plate

11. Yolk
Endoderm
Mesoderm
Neural fold
Anterior neuropore
pharynx
Oral plate
Subcephalic pocket

12. 6 6
1 4 5
4
7 2
3
3 7 1
1 – amnio-cardiac vessicle
2 – notochords
3 – splanchnopleure
4 – head mesenchyme
5 – neural groove
6 – neural fold
5 and 6 – neural tube
7 – cardiac primordia (thickened splanchnic mesoderm)

13. 1
4 2
3 4
5
1 – neural fold
2 – neural groove
1 and 2 – neural tube
3 – notochord
4 – pharyngeal pouches
5 – anterior intestinal portal / midgut

15. Primitive Pit

17. Procencephalon
Mesencephalon
Rhombencephalon
Ventricle
Omphalomesenteric veins
Spinal Cord
Somites
Notochord
Sinus Rhomboidalis

18. 15
14 11
13
16 10 4
3
12 9 7 2
6 1
8 5
1 – proamnion 9 – margin of the anterior intestinal portal
2 – prosencephalon 10 - anterior intestinal portal
3 – mesencephalon 11 – auditory vesicle?
4 – rhombencephalon 12 – somites
5 – optic vesicle 13 – notochord
6 – bulbus cordis? 14 – spinal cord
7 – ventricle 15 – sinus rhomboidalis
8 – vitelline veins 16 – blood islands

19. 7 8
8
1 – prosocoel
2 – optocoel
3 – Head Ectoderm
4 – Proamnion
5 – subcephalic pocket
6 – infundibulum
7 – head mesenchyme
8 – optic vesicle

20. 8
1 – mesocoel
2 – Head Mesenchyme
3 – Dorsal Aorta
4 – Aortic Arch
5 – Ventral Aorta
6 – Oral Plate/Membrane
7 – Notochord
8 – Foregut

22. 10
1 – Head Ectoderm 9 – rhombocoel
2 – Foregut 10 – dorsal mesocardium
3 – Ventricle
4 – Pericardial Cavity
5 – epimyocardium
6 – endocardium
7 – Thyroid Rudiment?
8 – dorsal aorta