Ciliary beating plane and wave propagation in the bovine oviduct.

The uterine tube is an essential conduit for the gametes and zygote during reproduction. The necessary bidirectional conveyance occurs through peristalsis and ciliary activity, but unlike in respiratory tract, little is known about mucociliary transport in the uterine tube, and the direction of transport and the alignment of oviductal cilia have not been conclusively characterized. This study aimed to determine the uniformity in the axonemal orientation of motile cilia in the bovine uterine tube, to identify the direction of mucociliary transport and to relate the presumptive beating plane and the mucociliary transport direction to the long axis of the uterine tube. The angular spread of oviductal motile cilia was determined by electron microscopy, and by maintaining the accurate alignment of the samples throughout the processing steps, axonemal orientation was determined relative to the long axis of the oviduct. The direction of the effective mucociliary transport was determined by the analysis of video microscopic data recorded on explants. Vector-based analysis of electron micrographs yielded the mean angle of deviation between the 'effective ciliary stroke', as derived from axonemal orientation, and the tubal longitudinal axis pointing towards the uterus to be 0.8°, with a standard deviation of 35.2°. The corresponding angular deviation of the short-wave propagation was -6.8° (SD 34.6°). These results show that oviductal motile cilia are rigorously aligned, that the beating plane of the cilia is parallel to the long axis of the uterine tube and that the 'effective stroke' and mucociliary transport are directed towards the uterus.