Self organized vessel navigation in jellyfish (aurelia aurita)

Abstract

The development of a primitive vascular circuit into a hierarchical vascular network involves an interplay between genetic determination and physical self organisation. We investigated the navigation of newly sprouting vessels in jellyfish and the possible contribution of mechanical stress involved self organization. With microscopic shadowgraphing we observed ~3 months old jellyfish while lying on its back in shallow seawater such that the muscle at the rim of its umbrella is able to slightly contract. The ‘arteries’ (black) of the gastrovasculature are straight, while the ‘veins’ (gray) have a strong dichotomous branching structure. We observed that newly formed veins typically sprout off from the large circular vein in the middle between 2 existing vessels and then navigates towards an already existing vein to which it will connect. Sprouting starts with centripetal buckling of the circular vein due to contraction of the muscle at the rim. With a simple finite element model we calculated the laplacian deformation in response to in-plane stresses imposed by the high pressurized artery and low pressurized vein. These calculations show that sprouts will grow spontaneously towards the softer existing vein. We conclude that besides possible chemical gradients of growth factors also physical self organization plays an important and maybe dominant role in vessel navigation.