Sperm Transport – Mechanisms of Male Contraception

The human reproductive system is a complex set of intertwining factors, many of which are required for sustained fertility. By interrupting even a single one of these required processes, we can find new ways to create exciting non-hormonal contraceptives for men. One process is sperm transport, or how sperm move through the male reproductive tract.

​Stopping Sperm Transport – An Old Idea Made New

After sperm are created in the testis, but before they demonstrate motility and fertilize an egg, they must be expelled by the body in a process called ejaculation. Upon ejaculation, sperm are moved from the epididymis to the vas deferens. From there, they move to the urethra, and then out into the wild world. Preventing sperm from being transported out of the reproductive tract isn’t a new idea. In fact, it’s the basis of one of the only existing forms of male contraception – vasectomy.

The vas deferens are sealed to prevent transport of sperm from the epididymis to further stages in the reproductive tract. Photo by K.D. Schroeder, distributed under a CC BY-SA 3.0 license.

In a vasectomy, the vas deferens are cut and tied, or sealed to prevent sperm from exiting the body. It’s a simple and effective process. Unfortunately, vasectomy reversal isn’t reliable enough for this to be considered a non-permanent method.
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However, there are multiple groups working on reversible vasectomy, or what we call vas-occlusive devices. These devices work similar to a vasectomy, but instead of cutting the vas deferens, a gel is inserted to block the flow of sperm while allowing fluid movement. Vas-occlusive devices are intended to be easily reversed at the user’s discretion. Some products such as ADAM™ and Vasalgel propose to do this either through natural degradation of the gel, or by a simple restoration procedure.

Vas-occlusive devices can bring about a new long-term management of fertility for men – one that is reversible. These devices could act for years on end, and would require no maintenance or pill-taking on the part of the user.

There are also pharmacological approaches to prevent sperm transport. MCI has funded Sab Ventura of Monash University in Australia to develop his program, which prevents sperm transport by blocking smooth muscle contractions.

There’s more than one way to contracept.

​Reproduction is a big, complicated machine, with lots of ways to put a temporary hold on the process. Preventing sperm transport is one way that to make the next generation of male contraceptives. Other projects focused on preventing spermatogenesis, sperm motility, and fertilization are all being actively pursued.

Together, we’re hopeful that these scientific ventures create multiple forms of male contraception with diverse product profiles that meet the needs of more users.

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Nuts & Bolts: Sperm Transport

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male reproduction and contraception

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