Vascular Collateralization Investigated in the Chorio‐Allantoic Membrane (CAM)

Abstract

IntroductionCollateralization upon obstruction of an arterial vessel is crucial to maintain tissue perfusion. The aim of this study is to quantify the dynamics of structural adaptation on the microvascular level in a model where vascular reactions can be observed continuously.MethodWhite leghorn chicken eggs were transferred on incubation day E3 into petri dishes. On E12, a selected arteriole of the CAM was occluded by laser irradiation. At several time points before and after occlusion, the area perfused by the arteriole was scanned using video microscopy. Blood flow velocity in selected vessels in the recorded area was measured (spatial correlation) and hemoglobin oxygen saturation was determined (hyperspectral analysis).Results and ConclusionBefore occlusion, the occluded arterioles were 64.86 ± 6.33 µm in diameter and microvasculature displayed an interdigitated pattern of arterioles and venules. Flow velocities exhibited a strong linear decline with decreasing vessel diameter. After the occlusion, functional collaterals were typically observed either between one daughter arteriole and an adjacent arteriole not fed by the obstructed vessel or between one daughter and the upstream sister arteriole. They developed from pre‐existing terminal arterioles (3 of 20) and/or by remodeling of capillary meshes (17 of 20). Collateralization resulted in reversal of flow in arterioles downstream of the occlusion. It is concluded that in the CAM model, collateralization maintains local microcirculatory function via pre‐existing arterial anastomoses vessels or via capillary meshes.Supported by EU / ITN “REVAMMAD” # 316990