Hypertrophy of radial and ulnar arteries following denervation of the chicken wing.

Denervation of radial and ulnar arteries in the growing and adult domestic fowl was achieved by unilateral sectioning of the brachial plexus. Eight weeks later the denervated arteries and those of the contralateral wing were examined with light- and electron microscopy to determine the effect of denervation on arterial structure. In growing fowls, the area of the media in radial and ulnar arteries was increased by 29% and 25%, respectively, after denervation. The number of smooth muscle layers was also significantly increased by 16% (radial) and 14% (ulnar), but no significant variation was seen in the wall/lumen ratio of either growing artery. In adult fowls, the area of the media was increased by 93% (radial) and 32% (ulnar) following denervation and the number of smooth muscle cell layers increased by 39% (radial) and 11% (ulnar). There was also an increased wall/lumen ratio of 64% (radial) and 92% (ulnar). These results indicate that hyperplasia of smooth muscle has occurred in response to denervation. Flow-cytometric DNA analysis of growing arteries also indicates that the increase in muscle-cell volume is a result of cell division (not polyploidy) since no significant differences were found between the control and denervated arteries in any stages of the cell cycle.