Biology of Reproduction, Vol 23, 904-909, Copyright © 1980 by Society for the Study of Reproduction

Contractions of the Rabbit Vas Deferens Following Sexual Activity: A Mechanism for Proximal Transport of Spermatozoa

¹ Department of Physiology and Biophysics, and Department of Obstetrics and Gynecology, University of Illinois at the Medical Center, Chicago, Illinois 60680

Previous work from this laboratory has shown that during the period of rest following sexual activity the contents of the vas deferens are transported toward the epididymis, i.e., in the proximal direction. To elucidate the mechanism responsible for this transport, the contractile activity of the vas deferens was monitored. Radiographic dye was injected into the lumen of the vas deferens of 10 adult male rabbits 4-6 days before recordings were made. Prior to anesthesia, given at the time of contractile recording, each animal was sexually stimulated and proximal transport of the dye was confirmed radiographically. Two microminiature strain gauges were subsequently attached to the abdominal vas deferens 2 cm apart, and activity was monitored for 2-5 h. Spontaneous contractions were observed in all vasa during this poststimulation period. While each duct had its own pattern of contractile activity, the parameters were comparable from animal to animal. Mean values (± SEM) for distal and proximal parameters were, respectively: amplitude, 889.5 ± 101.3 and 497.4 ± 39.6 µV; frequency, 2.84 ± 0.19 and 2.49 ± 0.18/min; duration, 18.6 ± 0.9 and 16.4 ± 0.8 sec; percent time in the contractile state, 79.7 ± 2.3 and 69.0 ± 3%. All distal parameters were significantly (P<0.05) greater than those observed in the proximal vas. This demonstrates that the distal vas deferens possesses greater contractile activity than the proximal duct after sexual activity and may therefore explain the transport of vasal contents back to the epididymis following a sexual encounter. The results further suggest that the vas deferens is an active organ during sexual rest, possibly aiding in the regulation of sperm reserves.

Note:
ACKNOWLEDGMENTS The force transducers were a gift from Drs. T. S. Nelsen and P. W. Barth at Stanford University which was made possible by NICHD Contract No. N01-HD-3-2774. The authors wish to express their appreciation to Dr. S. F. Marotta for valuable advice throughout this work.