Adrenergic Nerve Terminals in Collateral Arteries of the Lower Extremity

Abstract

The distribution of adrenergic nerve fibers to collateral arteries after ligation of the femoral artery was studied with the aid of the specific fluorescence technique of Falck and Hillarp. The extramuscularly located proximal and distal parts of the collateral pathway showed only sparse adrenergic innervation, while the intramuscularly located arteries were surrounded by a fairly dense network of adrenergic fibers. The adrenergic nerve terminals were found in the adventitia and penetrated the media for only a short distance. The collateral arteries were found to have the same pattern of adrenergic innervation as the corresponding arteries on the control side. The distances between the individual adrenergic fibers of the collateral arteries appeared to be greater than those in the control arteries, owing to the larger outer circumferences of the collateral vessels. The response to sympathetic nerve impulses and to myogenic propagation of impulses is discussed in relation to some morphological features of the collateral arteries.