On the Mechanism for Flow in the Efferent Ducts

A cilio‐peristaltic model for pumping of efferent duct (ED) contents that predicts the observed volumetric flow rates and is consistent with a positive pressure gradient toward the epididymis is proposed. The model predicts that the major contributor to fluid flow is the peristaltic component. The cilia, in contrast, may reduce flow by creating reflux. This effect may be reduced considerably with an increase in fluid viscosity, which is in turn a function of sperm concentration. It is concluded from this investigation that if the peristaltic wave has a 33% or more constriction, the spermatozoan concentration in the ED is at least 4 × 108 cells cm−3 and flow rates in the ED are the same as in the rete testis; then transit in the ED is due to cilio‐peristaltic pumping.