The aortic arch - the structure formed by the body's largest artery, the aorta, as it leaves the heart - lies on the left of the body's midline, defying the symmetry found in most bodily structures. However, it forms from a symmetrical network of blood vessels present during development. New research published in Nature helps to fill in the genetic pieces of this developmental jig-saw puzzle.
Hiroshi Hamada and colleagues studied mice lacking a gene called Pitx2, and found that these mice end up with an aortic arch found randomly on either the left or right side. They conclude that Pitx2 expression does not directly lead to asymmetric blood-vessel development, but rather sets up an asymmetric blood supply that differentially influences the expression of growth factors at different locations in the developing vascular system.
Thus, this asymmetric blood flow prompts a relatively innocuous blood vessel called the sixth branchial arch artery to develop into the main vessel through which all of the body's arterial blood passes on its journey around the body.
Hiroshi Hamada (Osaka University, Japan)
Kenta Yashiro (Barts & The London Queen Mary's School of Medicine & Dentistry, London, UK)
(C) Nature press release.
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