The epididymis is a narrow, tightly-coiled, duct-like organ that plays a major role in male infertility. It connects the testis to the vas deferens, and the sperm attains most vital functions while passing through it.
Epididymis is the main reason for sperm maturation and motility. Any damage or defect in the organ can hinder the sperm’s ability to fertilize the eggs.
In this article, let’s look at the significance of epididymis and the role it plays in male fertility.
What is the Significance of Epididymis in Male Fertility
Once the testes produce sperm, these immature sperm are transported through the epididymis to the vas deferens. While traveling through the epididymis, the immature sperm are exposed to various fluids, allowing them to mature and swim. Below are some of the major functions of the epididymis.
Sperm transport
The epididymis is responsible for transporting the sperm from the testis to the vas deferens. The epididymis is approximately 6–7 meters long, so it might take about 4–6 weeks for the sperm to travel from the testis to the vas deferens.
During this travel, the sperm increases in concentration, becomes fully mature, and gains the ability to swim and fertilize the eggs.
Sperm concentration
The immature sperm produced by the testes are not concentrated enough to mature. During the transit through the epididymis, the sperm are exposed to some fluids that they absorb to become more concentrated.
This increase in sperm concentration can also make sperm more concentrated in the semen.
Sperm protection
The epididymis excretes antioxidant enzymes such as superoxide dismutase into the epididymal lumen. These enzymes protect the sperm from the external environment by neutralizing reactive oxygen produced by epithelial cell metabolism.
The epididymis also contains a blood-epididymis barrier, which protects mature sperm from the immune system and other potentially dangerous elements in the bloodstream.
Sperm storage
Once the sperm are matured and gains motility, they are sent to the tail (cauda) of the epididymis for storage. The sperm are stored here in a dormant state until ejaculation.
The tail is the smallest and longest part of the epididymis. They store up to 50–80% of the sperm produced at a given period. They also have epithelial cells that produce factors that keep the environment luminant for the sperm.
During ejaculation, the dormant sperm become active and travel to the vas deferens, where they are mixed with the semen and ejaculated.
Sperm maturation
Sperm maturation is an important factor in determining whether it can fertilize an egg. Even if the sperm has good motility and reaches the egg, if it is not mature enough, the sperm can’t fertilize the egg.
During their transit through the head and body part of the epididymis, the sperm are exposed to various fluids that make them more concentrated and aid in their maturation.
Acquisition of motility
The sperm won’t have the ability to swim when the testis first produces them. It is only after traveling through the epididymis do they acquire motility.
The sperm can also acquire motility under artificial conditions. But the epididymis provides the best conditions for them to acquire motility and undergo several structural and morphological changes to gain motility and have the best chances at fertilization.
Fertilization capabilities
Apart from aiding in maturation and motility, the epididymis also provides sperm with the necessary factors to penetrate the egg’s outer shell (zona pellucida).
They also provide sperm with proteins necessary for sperm-oocyte (egg) binding. The oligosaccharides on the egg membrane and the protein on the sperm membrane aid in this binding.
Conclusion
From what we saw above, we can learn that the epididymis plays an important role in male fertility. Only when the epididymis successfully matures the sperm can they swim through the uterus and fertilize the egg.
If couples cannot get pregnant after a long time of trying, and the female has no fertility issues, there is a high chance that the male has fertility issues. Whatever the case, it is best for couples to visit a fertility doctor if they have problems conceiving.
