A structural analysis of the myogenic control systems of the human Fallopian tube.

The structural basis for myogenic and neurogenic control of motility of human Fallopian tubes was studied. In the ampulla distinct muscle layers were absent, and bundles of cells oriented in different axes were in contact with one another by means of randomly located simple apposition contacts; no nexuses were present. The organization was consistent with a spread of electrical activity in either direction throughout all muscle bundles. Nerves were not found in close proximity to muscle and were mostly peripheral, surrounded by connective tissue sheaths and by Schwann cells within the sheath. They could play little role in control of ampullar motility. In the isthmus muscle bundles were grouped into innermost longitudinal layer, circular layer, and outermost layer of mixed orientation. Cell-to-cell connections were mainly by simple apposition contacts; no nexuses were found. There were such connections between cells of bundles oriented in different axes. The organization of muscles suggested that electrical activity could spread in either direction and throughout all layers. Nerves like those in the ampulla were located peripherally, and smaller bundles without connective tissue sheaths were in circular muscle. Few close contacts between nerve and muscle were observed.