E X P E R I M E N T S ON EMBRYONIC AORTIC ARCHES 339
by Stephan (1952) in his 5 cases and by Le Douarin and Le Douarin
(1959) in their 6 cases. The material in Fig. 4 (Rychter, 1957) is based
on 55 embryos.
The substitute arcus aortae may be formed by only one left ventricular aortic arch (Fig. 4a, c, g) or by two (Fig. 4b, d, f) or even by all
three left ventricular aortic arches (Fig. 4e). In some cases (12-7%) no
arcus aortae arising from the left ventricle developed and a vessel
pattern called 'dissociation' (Rychter, 1957) appeared (Fig. 4h). In
these embryos the brachiocephalic ducts alone were supplied with blood
from the left ventricle while the rest of the embryo as well as the embryonic membranes were supplied by right ventricular blood. In most
cases (76-4%) the arterial arch from 3 D took part in vicarious formation
of an arcus aortae alone or in combination with others. The right 3rd
aortic arch, therefore, is the main substitute blood channel after
elimination of the right 4th aortic arch.
The substitute arcus aortae formed by 3D or 3s can be distinguished
from that formed by 4D or 4 S by the position of the root of the corresponding subclavian artery. If the arcus is formed by either 3rd aortic
arch the subclavian origin is at the summit of the arcus (Fig. 4a-f.)
This pattern was not understood by Rubsaamen and Schellong (1953)
and Schellong (1954). However, in those cases where, on the corresponding side, only a primitive subclavian artery developed (e.g.,
Fig. 11—6 D 4D3D, b) it is not possible to define the origin of the developed arcus aortae without knowledge of the preceding local experimental intervention.
Between a completely developed substitute arcus aortae and mere
persistence of a thin or even cord-like dorsal aorta connecting the
neighbouring arches, there exists a series of transitional stages (Fig.
19b—6 D 4 D 3 S 4 S ).
The results of operations with one clip indicate that there might be
some mutual haemodynamic relations between various aortic arches
(e.g., between 4 D and 3 D or between 6 D , 6 S and 4 S ), which will be
elucidated in the following part.
B. Simultaneous Suppression of Two or Three Aortic Arches
From Table 1 it is apparent that there are 15 two-clip and 20 threeclip combinations. Stephan (1952) recorded 6 of them (in 35 embryos),
but a further 3 combinations can be discerned in his material. Rychter
(1961b) used 520 embryos to cover all 35 combinations.
Unless the developing arcus aortae (4 D ) or both pulmonary arches
(6 D 6s) were suppressed, the results were practically a summation of
the results obtained by individual aortic arch elimination (e.g., Fig. 5,
Fig. 6—3 D 3 s 4s).
by Stephan (1952) in his 5 cases and by Le Douarin and Le Douarin
(1959) in their 6 cases. The material in Fig. 4 (Rychter, 1957) is based
on 55 embryos.
The substitute arcus aortae may be formed by only one left ventricular aortic arch (Fig. 4a, c, g) or by two (Fig. 4b, d, f) or even by all
three left ventricular aortic arches (Fig. 4e). In some cases (12-7%) no
arcus aortae arising from the left ventricle developed and a vessel
pattern called 'dissociation' (Rychter, 1957) appeared (Fig. 4h). In
these embryos the brachiocephalic ducts alone were supplied with blood
from the left ventricle while the rest of the embryo as well as the embryonic membranes were supplied by right ventricular blood. In most
cases (76-4%) the arterial arch from 3 D took part in vicarious formation
of an arcus aortae alone or in combination with others. The right 3rd
aortic arch, therefore, is the main substitute blood channel after
elimination of the right 4th aortic arch.
The substitute arcus aortae formed by 3D or 3s can be distinguished
from that formed by 4D or 4 S by the position of the root of the corresponding subclavian artery. If the arcus is formed by either 3rd aortic
arch the subclavian origin is at the summit of the arcus (Fig. 4a-f.)
This pattern was not understood by Rubsaamen and Schellong (1953)
and Schellong (1954). However, in those cases where, on the corresponding side, only a primitive subclavian artery developed (e.g.,
Fig. 11—6 D 4D3D, b) it is not possible to define the origin of the developed arcus aortae without knowledge of the preceding local experimental intervention.
Between a completely developed substitute arcus aortae and mere
persistence of a thin or even cord-like dorsal aorta connecting the
neighbouring arches, there exists a series of transitional stages (Fig.
19b—6 D 4 D 3 S 4 S ).
The results of operations with one clip indicate that there might be
some mutual haemodynamic relations between various aortic arches
(e.g., between 4 D and 3 D or between 6 D , 6 S and 4 S ), which will be
elucidated in the following part.
B. Simultaneous Suppression of Two or Three Aortic Arches
From Table 1 it is apparent that there are 15 two-clip and 20 threeclip combinations. Stephan (1952) recorded 6 of them (in 35 embryos),
but a further 3 combinations can be discerned in his material. Rychter
(1961b) used 520 embryos to cover all 35 combinations.
Unless the developing arcus aortae (4 D ) or both pulmonary arches
(6 D 6s) were suppressed, the results were practically a summation of
the results obtained by individual aortic arch elimination (e.g., Fig. 5,
Fig. 6—3 D 3 s 4s).