The lumina of the vasa efferentia expand into renal corpuscles as they approach the Wolffian ducts (Figs.
Only the Plethodontidae lack a renal corpuscle (character 7, state 1) separating the vasa efferentia from the more distal epididymal ducts Too little data are available to recover ancestral state for salamanders in terms of Wolffian ducts without ciliated cells (character 8, state 0) or Wolffian ducts with ciliated cells (character 8, state 1) The branches leading to the Ambystomatidae + Dicamptodontidae + Salamandridae and Rhyacotritonidae possess Wolffian ducts with ciliated epithelial cells, whereas the branches leading to the Plethodontidee and Proteidae do not possess ciliated Wolffian ducts.
In general, vasa efferentia transport sperm from the testes into modified nephrons.
In the Eurycinae, no renal corpuscle or Bidder's duct is observed and, thus, distinguishing between the vasa efferentia and the afferent and efferent epididymal ducts is difficult.
Whereas a renal corpuscle delineates the vasa efferentia from the efferent epididymal ducts, no longitudinal duct connects the vasa efferentia and no discernible afferent epididymal duct exists between the renal corpuscle and the vasa efferentia.