Fig. 15.

Sympathetic nerves were absent in loops of intestine subjected to chronic external denervation. TH immunoreactivity was used as a marker for the sympathetic innervation, which in turn served as an indicator of the completeness of extrinsic denervation. The dense array of varicose TH-immunoreactive nerve fibers can be seen in both the submucosal (A) and myenteric (C) plexuses of control loops of gut from the operated animals. In contrast, the denervated loops of intestine from the same animals contain no TH-immunoreactive nerve fibers in either the submucosal (B) or myenteric (D) plexuses. Notice that the perivascular TH-immunoreactive fibers are also lacking in the submucosa of the denervated loops of gut. The same results, showing that the extrinsic innervation was eliminated, were obtained in three of three operated guinea pigs. Scale bar, 100 μm.