- Aortic septum
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Heartof human embryoof about thirty-five days, opened on right side. (Aortic septum labeled at center right.)
Caption2 = Diagrams to show the development of the septum of the
aortic bulband of the ventricles. (Aortic septum labeled at center top.)
In the developing
heart, the truncus arteriosus and bulbus cordisare divided by the aortic septum. This makes its appearance in three portions.
(1) Two distal ridge-like thickenings project into the lumen of the tube; these increase in size, and ultimately meet and fuse to form a septum, which takes a spiral course toward the proximal end of the
truncus arteriosus. It divides the distal part of the truncus into two vessels, the aorta and pulmonary artery, which lie side by side above, but near the heart the pulmonary arteryis in front of the aorta.
endocardial cushionsappear in the proximal part of the truncus arteriosus in the region of the future semilunar valves; the manner in which these are related to the aortic septum is described below.
(3) Two endocardial thickenings—anterior and posterior—develop in the bulbus cordis and unite to form a short septum; this joins above with the aortic septum and below with the ventricular septum. The septum grows down into the ventricle as an oblique partition, which ultimately blends with the ventricular septum in such a way as to bring the bulbus cordis into communication with the
pulmonary artery, and through the latter with the sixth pair of aortic arches; while the left ventricle is brought into continuity with the aorta, which communicates with the remaining aortic arches.
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