Cell contacts and distribution of nerves in the smooth muscle of estrogen-dominated rabbit oviduct.

The types of cell-to-cell contacts and the relationship between the nerve endings and the smooth muscle of the estrogen-treated rabbit oviduct have been investigated. The cell contacts most consistently found in the oviduct were simple appositions, with a 20-nm cell separation, which occasionally included a more dense region, and interdigitations of muscle cell processes with the same separation distances. Very rarely, wider intermediate contacts were present. Gap junctions (nexuses) were absent. It seems likely that simple appositions and interdigitations form the low resistance pathway for conduction of electrical activity. Nerves containing small dense-cored vesicles were present both within and near muscle bundles; they were rarely found close to smooth muscle cells.