Microvascular hemodynamics in the chick chorioallantoic membrane

Abstract

Objective The microvasculature of the chorioallantoic membrane (CAM) in the developing chick embryo is characterized by interdigitating arteriolar and venular trees, connected at multiple points along their lengths to a mesh-like capillary plexus. Theoretical modelling techniques were employed to investigate the resulting hemodynamic characteristics of the CAM. Methods Based on previously obtained anatomical data, a model was developed in which the capillary plexus was treated as a porous medium. Supply of blood from arterioles and drainage into venules were represented by distributions of flow sources and sinks. Predicted flow velocities were compared with measurements in arterioles and venules obtained via video microscopy. Results If it was assumed that blood flowed into and out of the capillary plexus only at the ends of terminal arterioles and venules, the predicted velocities increased with decreasing diameter in vessels below 50 μm in diameter, contrary to the observations. Distributing sources/sinks along arterioles/venules led to velocities consistent with the data. Conclusions These results imply that connections to the capillary plexus distributed along the arterioles and venules strongly affect the hemodynamic characteristics of the CAM. The theoretical model provides a basis for quantitative simulations of structural adaptation in CAM networks in response to hemodynamic stimuli.

Novel morphometric analysis of higher order structure of human radial peri-papillary capillaries: relevance to retinal perfusion efficiency and age

“…Traditional modelling of capillary beds focused on bifurcation of vessels 12 , but recently loops have been demonstrated in real capillary networks 13,14 , and we confirm that for the human radial peri-papillary capillaries 15,16 of this study. Topologically similar shunts or collaterals have been reported in heart vessel networks of older subjects 17 .…”

“…Loops are present in all levels of the human and rodent retinal vascular beds and are important in angiogenesis 3,20,77 . As mentioned, even fairly recent models of capillary beds do not include loops 12 , but recently loops have been demonstrated in real human 3 and rat 20 retinal capillaries, chick chorioallantoic membrane capillaries 13,14 , and coronary collaterals within the human heart 17 . We certainly saw them in our samples of the human retinal RPCs (asterix in Figs 2–4).…”

An angiogenesis platform using a cubic artificial eggshell with patterned blood vessels on chicken chorioallantoic membrane

“…3) A chick embryo takes in approximately 6 L oxygen for hatching during a 21-day incubation [ 61 ], and Romijn et al reported that there was a progressive fall of partial oxygen pressure (air cell) within the egg due to the increased oxygen consumption by the chick embryo as it grew larger [ 62 ]. In the current study, low air pressure was measured only after blood vessels spread initially on the lateral-side membrane, transporting nutrients and oxygen from the lateral-side membrane [ 63 ]. 4) The area and volume of the induced blood vessels became larger as the volume of the chamber increased, containing a larger oxygen volume.…”

Stimulation of the oxygen consumption by photobiomodulation in the chicken embryo chorioallantoic membrane during hypoxia

“…Such a broad distribution of the initial mtpO 2 can be explained by a pO 2 gradient that is present in the epithelial layer of the chorion membrane. As the embryo develops, a tree-like venules and arterioles evolve from an initially homogeneous capillary plexus [37]. Also, with the embryo development, blood vessels network involves more bifurcations, resulting in a heterogeneous distribution of the pO 2 within the CAM.…”