Myoelectrical activity and transport of unfertilized ova in the oviduct of the mouse in vitro.

The relationship of myoelectrical activity to locations and movements of eggs was analysed in 12 mouse oviducts in vitro. When the eggs were in the ampulla the ampullary activity did not spread through the ampullary-isthmic junction (AIJ), and a narrow region of activity of lower frequency separated the ampullary and isthmic activities. When the eggs were in the isthmus the activity beginning on the isthmic side of the AIJ spread towards the uterus for progressively longer distances. Eggs were near or at the front of the plateau formed by this activity. A separate activity arising in one or more areas of the uterine side of the plateau often spread in the ovarian direction, thus opposing movements of eggs and fluid in the uterine direction. Transport of unfertilized eggs appears to be regulated by a small number of relatively stable pacemakers in the mouse oviduct.