Development and initiation of sperm motility in the hamster epididymis

Abstract

Hamster spermatozoa were isolated from the caput, corpus and cauda epididymidis. They were observed in culture medium at 37°C with a phase-contrast microscope and their motility recorded cinematographically. About 20% of the caput epididymidis spermatozoa were motile and moved in a confined space with no forward progression. 30% of the corpus epididymidis spermatozoa were motile, showing increased flagellar activity and moving in wide circles. 90% of the cauda epididymidis spermatozoa were motile and moved forward. Forward motility was induced in immotile spermatozoa from the caput epididymidis by adding cyclic 3'-5' adnosine monophosphate (cAMP) phosphodiesterase inhibitors (caffeinem theophylline, IMX) and epididymal plasma. The best stimulation was initiated by 15 mM caffeine with 10% of cauda epididymal plasma; a mean of 60% of forward motility was obtained which lasted for one hour and then ceased. Cinematographic studies revealed that some induced sperm movements differed from the equivalent natural ones by the amplitude of the head movements. It is shown that during epididymal transit of hamster spermatozoa, the induction of forward motility requires not only an increased cAMP level but also factors from the cauda epididymal plasma. The idea that glycoprotein of epididymal origin initiates forward motility is discussed.