Regional variations in transport of the luminal contents of the rat epididymis in vivo.

The speed of transport of the luminal contents of the epididymis was studied by injecting small droplets of stained paraffin oil into the lumen in 10 different regions of the epididymal duct of 64 anaesthetized rats and measuring the distances the droplets moved in 2 h. The oil droplets became dispersed, and there was much variation between the animals. The dispersion distances were longest in the proximal caput and shortest in the corpus. The distributions of the transport distances of the oil droplets were discontinuous and multimodal in the proximal caput, and bimodal in the cauda. The transport speed decreased steeply from 420 mm/2 h in the most proximal caput to 64.2 mm/2 h in the beginning of the distal caput. In the rest of the caput, corpus and cauda, speed was quite similar although it declined slightly towards the ductus deferens, being 25.5 mm/2 h in the most distal region of the cauda.