Human males produce about 35,000 sperm cells per minute from each testicle. It takes two weeks from production for a single cell to be pushed along out of the testicle. They then pass into the epididymis.

The epididymis is a soft, long coiled narrow maturation tube. The most delicate part of the epididymis is very thin (50 microns in diameter – less than the thickness of a hair) and is surrounded by large thin- walled blood vessels which act as a heat exchange system during the time it takes for the sperm to mature. This requires a lower than normal body temperature, which is why these male organs are located outside the body cavities.

The epididymis is over 8 metres long with a sperm cell taking over one month to pass along its length. During this time the sperm develops and grows a tail and tough head – only able at this stage to function as a sperm.

The sperm leave the epididymis and enter the vas. The vas is wider and more muscular than the epididymis and is 1-2 mm in diameter. The actual bore/lumen that transports the sperm is 200 microns thickness (two to three hairs wide). Usually sperm cells will take a few more weeks to travel down the vas prior to ejaculation with the help of the prostate gland. So the total time from sperm production to ejaculation is two weeks in the testicle, four to six weeks in the epididymis and two weeks in the vas – eight weeks all together.

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