Sperm flagella: autonomous oscillations of the contractile system.

Bull sperm are deactivated, losing all motility, when they are impaled or dissected with a microprobe. Loss of activity is due to the creation of a hole or break in the cell membrane. Uncoordinated contractile activity is retained if external adenosine triphosphate and adenosine diphosphate are present. When these substances are in the medium, coordinated wave motion can be initiated in impaled or dissected sperm by bending a segment of the flagellum.