URETERAL STRUCTURE AND ULTRASTRUCTURE .1. NORMAL HUMAN URETER

Normal human ureters (28) were examined by light microscopy and EM. Uretero-trigonal units (3) were microdissected. The ureter is a non-layered muscular tube. The anatomical unit is muscle bundles that contain heterogeneously oriented muscle cells. Functional continuity of muscle cells is provided through the nexus, which are clearly defined structures. A group of morphologically distinct muscle cells were identified and these represented the ureteral pacemaker cells. The functional status of muscle cells causes certain morphologic changes and the cells fixed in contraction differ from those fixed in relaxation. In vitro testing of muscle cell contractility was feasible. The ultrastructure of the normal urothelium and the adrenergic and cholinergic components of ureteral nerves are presented briefly.