Experimental studies of rapid sperm transport in rabbits

When non-motile spermatozoa were used in seminal plasma for artificial insemination, rapid sperm transport to that oviducts was observed in every animal examined 15 min after insemination. Rapid transport never occurred when non-motile spermatozoa were suspended in artificial media, but when motile spermatozoa were suspended in artificial media they were frequently recovered from the oviducts within 15 min. Two successive artificial inseminations 15 min apart were each followed by rapid transport when both inseminates contained seminal plasma; when the second inseminate consisted of spermatozoa suspended in saline, only the first sperm population reached the oviducts. Rapid sperm transport was effectively blocked with the alpha-adrenergic antagonist phenoxybenzamine. We therefore conclude that: (1) sperm motility is not required for rapid sperm transport in rabbits, (2) constituents of the seminal plasma may initiate rapid transport by stimulation of vaginal contractions, (3) independent contractions of the uterus under control of the sympathetic nervous system may continue the transport process once the spermatozoa reach the uterus.