Hyperactivation may assist human spermatozoa to detach from intimate association with the endosalpinx

The behaviour of human spermatozoa was observed during incubationwith epithelial cells isolated from the isthmic and ampullarysections of human uterine (Fallopian) tubes.During incubation,spermatozoa were observed to bind to the epithelial cells ofthe tube (the endosalpinx), and individual spermatozoa attachedand detached at intervals.The kinematic characteristics of spermatozoaduring these behaviour patterns were determined. The resultsshowed that detached spermatozoa typically had an increasedcurvilinear velocity and amplitude of lateral head displacement,accompaniedby a decrease in their linearity. Significantly (P<0.01)more of the detaching spermatozoa were hyperactivated than werespermatozoa prior to attachment for both isthmic (35.3 ±5.5 versus 4.0 ± 3.3%mean ± SEM) and ampullary(26.0 ± 7.0 versus 2.0 ±1.4%) regions. Incubationwith epithelial cells from either region produced no differencesin any category of sperm behaviour. Furthermore, there was nosignificant difference between regions in the amount of timespermatozoa spent bound (33.6 ± 12.9 and 20.6 ±3.0 s for isthmic and ampullary tissue respectively). Theseresults support the hypothesis that hyperactivation may assistspermatozoa in breaking connections with epithelial cells.