Sympathetic system t-PA/EGFP expressions. (A) Cervical ganglion section: expression confined to neuron cell bodies and axons (inset, ×100). (B) Sympathetic chain longitudinal section: discrete expression confined within individual axons. (C)Adrenal medulla section: chromaffin cell nuclei show prominent expression (inset, ×100); cortex negative. (D) Lung: positve cross-cut fibers, presumed axons, dot all regions of the interstitium. Few appear in bronchial arteriolar walls (arrows and inset). (E) Brain surface: axon showing positive expression is embedded in wall of anterior cerebral artery branch (left). Positive expression is also evident in cross-cut and full-length individual axons (right). (F) Axon terminals heart surface: prominent expression by typical intermittent varicosities in the walls of a branching coronary arteriole (above) and in myocardium (below). Magnifications are ×40, except as noted.