In both in vitro and in vivo experiments, polycationic macromolecules, such as poly(L-lysine), inhibited the transport of either surrogate or freshly ovulated cumulus masses across the oviduct epithelial surface without affecting the ciliary beat. Whereas transport across the fimbria in vivo was completely inhibited, transport down the ampulla was 3 to 7 times slower than normal. The effects of these polycations suggest that cilia-mediated ovum transport may involve the formation of transient adhesive bonds between the tip of the cilium and elements of the cumulus mass during each beat cycle of the cilium.Numerous studies have shown that once the ovum with its surrounding cumulus mass is discharged from the ovary, it is rapidly transported over the fimbrial surface of the oviduct and down the ampulla to the ampullar-isthmic junction (1). The ovum remains at the junction for several hours where the cumulus mass is removed; eventually, the denuded ovum travels through the isthmus to the uterus. Until recently, it has been generally accepted that the cilia of the epithelial cells that line the oviduct are responsible for movement of the cumulus over the fimbria into the ampulla and that the contractile activity of the smooth muscle cells in the wall of the ampulla is responsible for transporting the cumulus down the oviduct to the ampullar-isthmic junction (14). However, recent experiments by Halbert et al. (5,6) have shown that pharmacological inhibition of smooth muscle contractility does not impair cumulus transport in the ampulla, which suggests that smooth muscle contractility may not be the primary propulsive force in this region of the oviduct. The effects of muscle activity alone on ovum transport in the ampulla have not been determined because of the unavailability of a method specifically to inhibit cilia activity.The coordinate beating of cilia creates fluid currents over the oviduct epithelial surface, and these fluid movements have been proposed to be involved in moving the ovum (7,8). If this is the mechanism of ovum transport, then the cumulus is a passive agent that i carried in a "stream" of fluid over the epithelial surface. The only way to interfere with this process would be to alter the beating of the cilia severely enough to eliminate the surface fluid currents.Recently we reported that the portion of the rabbit oviduct ciliary membrane that covers the tip of the cilium has a high density of negative charges (9). By using polycationic ferritin as a specific electron-dense probe for anionic sites, we have shown that the probe binds to the tips of the cilia and that this binding is probably due to the presence of sialic acid-containing proteins at this site on the membrane. Evidence from other workers suggests that this might be a general property of ciliary membranes (10).The existence of negative charges on a portion of the ciliary membrane that would most likely interact with elements of the cumulus mass during ovum transport suggests that some type of electrostatic interaction betwee...

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