The junctions between efferent ductules and epididymal duct in the boar

Sperm transit through the male excurrent duct system is dependent on complete luminal patency. Since male excurrent ducts are derived embryologically from originally separate structures, the junctions between mesonephric tubules and the mesonephric duct are of major interest with respect to obstructive disorders. Therefore, we investigated the junctions between efferent ductules and epididymal duct in adult boars by means of serial semithin and ultrathin sections. Based on the anastomosing pattern and on the site of transition from low columnar, ciliated epithelium to high columnar, non-ciliated epithelium, three different types of anastomoses were identified, one of which was associated with luminal stenosis and sperm accumulation. The occurrence of end-to-side junctions with the epithelial transition being localized within the lumen of the tributary may thus impede normal sperm transport.