Two-dimensional maps of short-term albumin uptake by the immature and mature rabbit aortic wall around branch points.

In children, aortic lipid deposition develops in triangular regions of the wall downstream of branch points, whilst in adults these regions are particularly free of disease. Comparable age-related patterns occur in rabbit aortas. They may be explained by patterns of wall permeability to circulating macromolecules: along the longitudinal midline through branches, permeability is greater downstream than upstream in immature rabbits, but is greater upstream at later ages. Here we have mapped permeability in detail around such branches, not just along the midline. Short-term uptake of rhodamine-labeled albumin, measured using digital imaging fluorescence microscopy of serial sections, was greatest in an approximately triangular region downstream of immature branches, but in mature animals it was greater upstream, particularly away from the midline, and in streaks to the side of branches. Hence the maps are consistent with earlier permeability data and closely resemble the patterns of disease.