Hemodynamics of the omphalo-mesenteric arteries in stage 18 chicken embryos and "flow-structure" relations for the microcirculation.
OBJECTIVE
The primary objective of this study is to evaluate the hemodynamic and structural characteristics of the omphalo-mesenteric (vitelline) arteries in stage 18 chicken embryos. The measured results were compared with Murray's law to validate the theoretical prediction on the vascular structure.


METHODS
Variation of hemodynamic parameters such as mean velocity (U(mean)), peak velocity (U(peak)) at the systolic phase, velocity fluctuations (U(fluc)) at the pulsatile frequency, and the Womersley number (Ω) were measured with respect to the geometric parameters including the bifurcation cascade level (BCL), vessel diameter (D), and distance (L) from the first bifurcation. They were assessed by using the time-resolved in vivo micro-PIV (particle image velocimetry) technique and the geometric information was obtained from the microscopic vessel images.


RESULTS
The effect of "branching of the vessel" on the variation of hemodynamic characteristics is similar to those of the "increase in distance" from the first bifurcation and the "decrease in vessel diameter". The flow quantities (U(mean), U(peak) and U(fluc)) decrease due to the increase in cross-sectional area ratio (γ=1.209=(∑D(daughter)(2))/D(mother)(2)), and the Womersley number also decreases as the bifurcation cascades (Ω«1).


CONCLUSIONS
The geometric parameters are closely related to the variation of hemodynamic characteristics. Murray's law with non-constant viscosity hypothesis would provide an insight on the two-phase nature of microvascular blood flows.
Lee
Jung Yeop
JY
Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Republic of Korea.
Lee
Sang Joon
SJ
D000818:Animals; D001158:Arteries / Q000196:embryology; D001783:Blood Flow Velocity; D002642:Chick Embryo; D006439:Hemodynamics; D008833:Microcirculation; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D012212:Rheology; D014816:Vitelline Duct / Q000098:blood supply*