Reviewer 2

1

1 – Head Process2 – Head Fold3 – Proamnion4 – Area Opaca5 – Area Pellucida6 – Primitive Plate

2

3

45

6

Hensen’s Node

Primitive Pit

Primitive Ridge

Primitive Groove

Area Pellucida

1

1 – Neural plate2 – Notochord3 – Epiblast4 – Hypoblast5 – Yolk darkly stained cells are Blood Islands

23

4

5

1

1 – Hensen’s Node2 – Blood Islands3 – Epiblast4 – Hypoblast

2

3

4

1

1 – Primitive Pit2 – Primitive Knot3 – Epiblast4 – Hypoblast

2

3

4

1 – Primitive Groove2 – Primitive Ridge

1

2

Primitive Gut

Neural Fold

Anterior Neuropore

Neural Groove

Head fold

Somites

Unsegmented Mesoderm

Hensen’s Node

Blood islands

1 – Anterior Neuropore2 – Head Fold3 – Neural Groove4 – Neural Fold5 – Somites6 – Primitive Streak7 – Area Pellucida8 – Hensen’s Node9 – Unsegmented Mesoderm

8

9

Neural Tube

5

1 – Blood Islands2 – Thickened Splanchnic Mesoderm3 – Intersomitic Grooves4 – Notochord5 – Margin of the Anterior Intestinal Portal6 – Head Fold7 – Margin of the Foregut8 – Anterior Intestinal Portal

67

8

Head Mesenchyme

Oral plate

Pharynx

Subcephalic pocket

Neural folds

Neural groove

Anterior neuropore

Neural fold

Anterior neuropore

pharynx

Oral plate

Yolk

Subcephalic pocket

Mesoderm

Endoderm

1

1

23

3

44

1 – amnio-cardiac vessicle2 – notochords3 – splanchnopleure4 – head mesenchyme5 – neural groove6 – neural fold5 and 6 – neural tube7 – cardiac primordia (thickened splanchnic mesoderm)

56 6

7

7

1

3 4

2

1 – neural fold2 – neural groove1 and 2 – neural tube3 – notochord4 – pharyngeal pouches5 – anterior intestinal portal / midgut

4

5

Primitive Pit

Mesencephalon

Rhombencephalon

Procencephalon

Spinal Cord

Notochord

Sinus Rhomboidalis

Somites

VentricleOmphalomesenteric veins

1 – proamnion2 – prosencephalon3 – mesencephalon4 – rhombencephalon5 – optic vesicle6 – bulbus cordis?7 – ventricle8 – vitelline veins

12

34

56

7

8

9

10

11

12

13

14

15

16

9 – margin of the anterior intestinal portal10 - anterior intestinal portal11 – auditory vesicle?12 – somites13 – notochord14 – spinal cord15 – sinus rhomboidalis16 – blood islands

1 – prosocoel2 – optocoel3 – Head Ectoderm4 – Proamnion5 – subcephalic pocket6 – infundibulum7 – head mesenchyme8 – optic vesicle

7

8

8

1 – mesocoel2 – Head Mesenchyme3 – Dorsal Aorta4 – Aortic Arch5 – Ventral Aorta6 – Oral Plate/Membrane7 – Notochord8 – Foregut

8

1 – Head Ectoderm2 – Foregut3 – Ventricle4 – Pericardial Cavity5 – epimyocardium6 – endocardium7 – Thyroid Rudiment?8 – dorsal aorta

10

9 – rhombocoel10 – dorsal mesocardium