Passage of spermatozoa through the epididymis of the boar (Sus scrofa domesticus).

Previous studies of epididymal transit in the pig have had insufficient animal numbers to provide a comprehensive picture of a continuous process. The present study attempts to addresses this issue. Radioactively labeled thymidine was infused into the testicular arteries of 48 sexually rested young adult boars of the Goettingen Miniature Pig breed. Hemicastrations were performed in random order in 2 animals daily on Days 21-24 following thymidine injection and in 4 animals daily on Days 25-41 and 43, 45, 47 and 49. Sperm obtained from 12 epididymal sites between the proximal caput and distal cauda were autoradiographically examined to record the percentage of labeled sperm and labeling intensity at different times after thymidine infusion. An initial surge of labeled spermatozoa emerged in the proximal caput 28 days after thymidine injection. After 2 d labeled sperm had arrived at the distal caput and, after another 2, the bulk of labeled sperm was found in the corpus. From there the sperm advanced to the transition of corpus and cauda, where progress was arrested until Day11. On Day 12, transit was resumed and by Day 13 sperm had passed through the cauda and vacated the epididymis via the ductus deferens.
(Copyright © 2020. Published by Elsevier Inc.)