VASCULAR TISSUE ADAPTATIONS IN END-TO-END AUTOLOGOUS ARTERIAL GRAFTS IN RATS - A MORPHOMETRIC ANALYSIS

Autologous vein grafts are employed extensively to bypass stenoses in the arterial circulation. More recently arterial segments have been us ed for such bypass surgery. In this study the adaptation of regenerati ng vascular tissues in experimental autologous artery grafts (4 mm lon g and 1 mm in diameter) in 20 adult male Wistar rats was analysed. At 1, 2, 4, 8 and 16 wk after insertion, 4 grafts per time interval were removed, processed for high resolution light microscopy and the thickn esses of the media and neointima, as well as the area fractions of smo oth muscle cells, were analysed morphometrically. All grafts were reen dothelialised by 2 wk. Neointimal hyperplasia (a subendothelial layer of smooth muscle cells) developed in all grafts and reached its maxima l thickness (40.4+/-4.7 mu m) at 2 wk. The area fraction of smooth mus cle cells in the neointima of the artery grafts did not change signifi cantly at any time from 2 to 16 wk. The media underlying the neointima of the artery grafts remained relatively constant throughout the 16 w k duration of the experiment. Whilst the total wall thickness of the g rafts reduced significantly between 2 and 4 wk after insertion, at all times the grafts were thicker than the host artery.