Vas deferens - Diagram

Vas deferens literally means ‘carrying-away duct’. It is a sperm duct that carries spermatozoa in anticipation of ejaculation.

Human males have two testes which are the primary sex organs. Vas deferens is part of the male reproductive system that is present posterior to the testis. Here, let’s look at the description of the vas deferens and the other associated testicular structures with the help of a labelled diagram.

Vas deferens – Description

• Testes are walnut-shaped structures that are suspended in a sac called the scrotum. Each testis measures 5×3 cm and weighs 15-19 grams.
• The testis is composed of finely coiled tubes called the seminiferous tubules that produce sperm. This seminiferous tubule continues further as vas efferens and then the epididymis.
• There is a delicate network of tubules in the testis called rete testis that carries spermatozoa from the seminiferous tubule to the vas efferens.
• At the posterior pole of the testis, the epididymis takes a sharp turn and continues as ductus deferens or vas deferens, without any demarcation. It is a sperm duct.
• The vas efferens, epididymis, vas deferens along with the rete testis forms the accessory sex ducts in males.
• The vas deferens is a muscular tube that transports spermatozoa through the epididymis to the two ejaculatory ducts.
• The accompanying artery provides blood supply to the vas deferens. Also, the vas deferens is innervated by different nerve endings.
• From the epididymis, the vas deferens pass into the abdominal cavity via the inguinal canal.
• The terminal part of vas deferens is called the ampulla. This ampulla joins the seminal vesicles of the same side to form the ejaculatory duct.
• Thus, two ejaculatory ducts are present and each of them receives sperm from the vas deferens and other secretions of the seminal vesicles. Both these ducts empty into a single urethra.

Significance

The smooth muscular walls of the vas deferens undergo peristaltic movement and push the sperm forward. It transports the sperm to the urethra and helps it prepare for ejaculation.

The prostatic fluid is emptied into the urethra through prostatic sinuses. The seminal vesicle secretions and the sperms from vas deferens are also emptied into the prostatic urethra through the ejaculatory ducts. The sperm, along with the prostatic fluid, is ejaculated as semen.

Any obstruction in the vas deferens will lead to infertility.

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