Epididymal origin of a coiled-tail sperm defect in a boar.

The development of a tail-coiling defect in spermatozoa from Welsh boar was studied by light and electron microscopy. The onset of tail-coiling was coincident with the passage of spermatozoa through the epididymis, since only cells isolated from regions of the duct distal to the caput epididymidis exhibited this characteristic. An intermediate form of this abnormality was detected in the proximal corpus epididymidis, where migration of the cytoplasmic droplets mainly occurred. It is suggested that defective migration of the cytoplasmic droplet might be associated with the pathogenesis of the coiled-tail defect in this animal.