Ultrastructure of Evolving Deep Venous Collaterals

Abstract

Objective:

To explore the structure of obstructive venous collaterals.

Design:

A total of 25 rats underwent unilateral ligation of the distal common femoral vein. Bilateral (control and test) vein segments with collaterals were harvested and studied with conventional light microscopy and electron microscopy at 2-week intervals for 10 weeks post-ligation.

Results:

Obstructive collaterals were quite unlike normal controls throughout the study. Initially, post-obstructive collateral walls showed disorganization of collagen, elastin, smooth muscle cells, and adventitia, while endothelial cells became more rounded and compact. The dense protein subendothelial deposits noted early became organized and moved more deeply into the wall at subsequent study intervals. Minimal motivation of smooth muscle cells, coalescence of elastic lamina, condensation of collagen and some organization of the wall were noted.

Conclusion:

Inability of deep collaterals to function with normal wall properties is likely to be secondary to the disruption of connective tissue and sustained disorganization of the vein wall noted throughout the evolution of collateral formation.