Twenty-four gilts were inseminated with live spermatozoa, dead spermatozoa (killed by rapid freezing and thawing) or a mixture containing an equal number of live and dead spermatozoa. Before insemination, the live spermatozoa were stained with fluorescene isothiocyanate. The females were killed 8 hr after insemination and spermatozoa were recovered from their reproductive tracts. Significantly more spermatozoa were recovered from the oviducts of gilts inseminated with live spermatozoa than from oviducts of gilts inseminated with either dead spermatozoa or the mixture. In gilts inseminated with the mixture, 54, 73, 71 and 100% of the spermatozoa recovered from the posterior half of the uterine horns, anterior half of the uterine horns, tubal flushings and the surface of ova, respectively, showed fluorescence.
In a second experiment, the left oviducts and right uterine horns were cannulated in eight gilts before cervically inseminating under anaesthesia with equal numbers of live-stained and dead spermatozoa. Fluid was collected from eight uterine and three tubal cannulae, the flow beginning within 1½ and 4½ min, respectively, after the onset of insemination. Both the volume of fluid collected and the concentration of spermatozoa in the fluid decreased with time after insemination, whereas the percentage of fluorescent spermatozoa increased. Dead spermatozoa were transported up the reproductive tract, but their transport was less efficient than that of live spermatozoa. Mechanisms of sperm transport are discussed.