Library · Physiology
Sperm transport
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A newly formed sperm cell is not ready yet. It leaves the seminiferous tubule, the little coiled tube inside the testicle where it is made, and it comes out immobile: it does not know how to swim. The rest of the trip is still ahead of it.
Its first stop is the epididymis, a very long coiled tube attached to the testicle. It spends about twelve days there, and that is where it acquires motility, meaning the ability to move forward on its own. Once that training is over, it is stored in the last part of the epididymis, the tail, waiting.
At ejaculation the real journey starts. The smooth muscle in the wall of the epididymis contracts and pushes it toward the vas deferens, and that duct carries it to the ejaculatory duct, right next to the prostate. Along the way fluids join it: the seminal vesicle contributes fructose, which is a sugar and therefore fuel for movement, and the prostate contributes its own fluid.
Any stretch of that route can fail. A disruption of that transport, for example when a duct is obstructed, is one of the causes of male infertility.
In brief
Sperm leave the seminiferous tubule immobile and travel to the epididymis to mature.
There they gain motility in about twelve days and wait in the tail of the epididymis.
They leave the factory unable to swim; they learn on the way.
At ejaculation, epididymal smooth muscle pushes them into the vas deferens, which carries them to the ejaculatory duct.
The seminal vesicle adds fructose, which fuels movement, and the prostate adds its fluid.
Impaired transport, including ductal obstruction, is one of the causes of male infertility.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Male Reproductive System, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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