Table 1. Showing correlation of size of embryos and development of the aortic-arch system.
|
Embryo No.
|
Length in mm.
|
Arches present.
|
Characteristic features.
|
Time of establishment of first arch; estimated average length 1.3 mm.; 23d day of development
|
1878
|
1.3
|
I
|
Slightly plexiform. Presomite stage
|
1201
|
2
|
I
|
|
391
|
2
|
I
|
7 somites
|
470
|
4
|
I
|
Neuropores open; 14 to 16 somites
|
2053
|
3
|
I; II beginning
|
Anterior neuropore closed; 20 somites; transverse anastomoses between primitive aortae
|
Template:CE1201b
|
3
|
I. II
|
Earlier mandibular aitery; paired longitudinal neural arteries;
|
836
|
4
|
II, III
|
no ventral tract on cord
|
Just before establishment of fourth arch; estimated average length 4 mm.; 31st day of development
|
826
|
5
|
III, IV
|
Earlier mandibular and hyoid arteries
|
1075
|
6
|
III, IV
|
Subclavian
|
588
|
4
|
III, IV
|
Earlier mandibular and hyoid arteries
|
873
|
6
|
III, IV
|
Ventral arterial tract on cord
|
988
|
6
|
III, IV
|
|
1380
|
4
|
III, IV, pulmonary arches almost complete
|
2841
|
4
|
III, IV; one so-called fifth arch; pulmonary almost complete
|
Early formation of basilar artery
|
Just before completion of pulmonary arch; estimated average length 6 mm.; 36th day of development
|
810
|
5
|
III, IV, and pulmonary arches
|
Late stage in formation of basilar artery, Splitting of aortic sac distinct. Unpaired aorta complete
|
1354
|
6
|
III, IV, and pulmonaiy arches
|
|
617
|
7
|
III, IV, two so-called fifth arches, and pulmonary arches
|
Subclavian artery surrounded by brachial plexus. Splitting of sac well marked. Islands at end of basilar artery
|
792
|
8
|
III, IV, and pulmonary arches
|
Pulmonary and IV arches widely separated below
|
1121
|
11
|
III, IV, and pulmonary arches
|
Right pulmonary artery small; basilar rounded; IV and pulmonary still farther apart
|
721
|
9
|
III, IV, and pulmonary arches
|
Cervical segmental arteries becoming interrupted
|
163
|
9
|
III, IV, and pulmonary arches
|
Anastomoses of cervical segmental arteries to form the vertebral artery are nearly complete
|
Time of interruption of pulmonary arch and of branchial period; estimated average length 12 mm 45th day of development
|
1771
|
13
|
III, IV, left pulmonary and remnant of right pulmonary arch
|
|
544
|
10
|
|
Vertebral artery complete; identity of arches disappearing; beginning of period of rapid descent of heart and arteries
|
940
|
14
|
|
Definitive aortic arch just taking form. Right dorsal aorta between III and IV interrupted. Remnants still distinguishable. Main pulmonary channel from heart to aorta nearly straight
|
1909
|
15
|
|
Common carotid elongated
|
492
|
16
|
|
Right dorsal aorta distal to IV patent but slender
|
Template:CE74
|
16
|
|
End of period of descent. Definitive aortic arch has curve of large radius. Short segment of right dorsal aorta distal to subclavian drawn out in slender thread
|
End of period of rapid descent of heart and arteries; estimated average length 18 mm.; 50th day of development
|
1390
|
18
|
|
Definitive aortic arch sharply bent
|
460
|
20
|
|
Summit of definitive aortic arch at superior thoracic aperture
|
2937
|
24
|
|
Sternal bands in contact through most of their length
|
886
|
43
|
|
Origin of right and left pulmonaiy" branches in contact through most of their length
|
Age estimates based on Keibel F. and Mall FP. Manual of Human Embryology II. (1912) J. B. Lippincott Company, Philadelphia. curve of length and age. Table as image Table Reference: Congdon ED. Transformation of the aortic-arch system during the development of the human embryo. (1922) Contrib. Embryol., Carnegie Inst. Wash. Publ 277, 14:47-110.
|