Light and scanning electron microscopic changes observed in experimental arterial forks of rabbits.

Experimental arterial forks were fashioned by anastomosing one common carotid artery to the contralateral vessel by microvascular surgery in rabbits. In one rabbit group the forks were examined histologically by the serial section technique from 5.5 to 25 months postoperatively. The second group was used for scanning electron microscopy of the arterial endothelial surface from 1 to 257 days post-operatively. Intimal proliferation was observed at the lateral angles histologically at sites comparable to those where intimal proliferation occurs spontaneously in human infants. In addition, disruption of the internal elastic lamina with minimal intimal proliferation occurred at the sides of the neo-apex, mostly in the transposed artery. These disruptions corresponded to predominantly transversely orientated tears of the internal elastic lamina from 8 days post-operatively in the scanning electron microscopic study. They were similar to the early atrophic changes preceding berry aneurysm formation in human cerebral arterial forks. The results indicate that both intimal pads (cushions) and elastic tears can be haemodynamically induced.