Male Sex Accessory Ducts: Description, Characteristics, Function

What are Male Accessory Ducts?

The male accessory ducts are the ducts that help transport sperm to the exterior of the body from the testes. The accessory ducts play significant roles associated with the process of reproduction and in semen formation.

Components of Male Accessory Ducts

The male accessory ducts include the epididymis, vas deferens, ejaculatory duct, and urethra. These structures are connected in a sequence that facilitates the movement of sperm from the testes to the exterior. The accessory ducts need to work efficiently to aid in human reproduction.

Epididymis

• The epididymis is a twisted, long tube lying on the posterior aspect of each testis, and it serves as a reservoir for sperm and the actual site of maturation of the sperm. Once the structure of sperm is formed, they are stored here.

• The epididymis is further divided into three parts. These are the head, body, and tail. The sperm that are formed in the testes are transported into the epididymis to undergo the process by which sperm are given the ability to move and the potential to fertilise an egg.

Vas Deferens

• The vas deferens is a muscular tube that carries mature sperm, after spermatogenesis and maturation, from the epididymis to the urethra.

• The tube is about 30 cm in length and passes from the scrotum into the pelvic cavity, curving over the top of the bladder on its way to the base to join the seminal vesicle.

• In addition, the vas deferens may also store sperm and may also be subjected to peristalsis, propelling sperm during ejaculation.

Ejaculatory Ducts

• The ejaculatory ducts are derived from the fusion of the vas deferens and the duct of the seminal vesicle.

• The two ducts go separately into the gland of the prostate to evacuate the content into the urethra, which enables the motility of the sperm and the seminal fluid during ejaculation.

Urethra

• The urethra is the terminal duct of the male reproductive system. It is bi-functional; that is, it acts as the channel for both the urinary and reproductive tracts.

• It carries the urine from the bladder and semen from the male reproductive system out of the body through the penis.

Functions of Male Accessory Ducts

These ducts store, mature, and transport sperm. They also play a key role in mixing sperm with seminal fluid during ejaculation for successful fertilisation.

1. Sperm Transport: The main function of the accessory ducts is to transport the sperm produced from the testes to the urethra for ejaculation.

2. Sperm Maturation: The maturation of sperm occurs in the epididymis, which is aimed at developing the sperm's motility and acquiring the potential to fertilise an egg. Sperm becomes semen via the vas deferens and the ejaculatory ducts, where the seminal fluid combines sperm from the seminal vesicles and the prostate gland.

3. Ejaculation: The sperm are expelled during sexual arousal from the body by the accessory ducts through the urethra.

MCQs on Male Accessory Ducts

Q1. What would be the likely consequence of the removal of the epididymis?

Option 1: The shortened lifespan of sperm

Option 2: Accelerated progression along the pathway

Option 3: Early functional maturation

Option 4: Impaired fertilization capability of sperm

Correct answer: 4) Impaired fertilization capability of sperm

Explanation:

The epididymis is a tightly coiled tube located on the back of each testes. It serves as a storage and maturation site for sperm. Sperm that are produced in the testes are transported to the epididymis, where they undergo further maturation and gain the ability to swim and fertilize an egg.

If the epididymis is removed, the sperm will not undergo the necessary maturation process. This would result in a reduced ability of the sperm to fertilize an egg. The epididymis provides the appropriate environment for sperm to acquire motility and other functional capabilities required for successful fertilization.

Hence, the correct answer is option 4) Impaired fertilization capability of sperm

Q2. If for some reason, the vasa efferentia in the human reproductive system gets blocked, the gametes will not be transported from

Option 1: testes to epididymis

Option 2: epididymis to vas deferens

Option 3: ovary to uterus

Option 4: vagina to uterus

Correct answer: 1) testes to epididymis

Explanation:

The male sex accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens.

The seminiferous tubules of the testis open into the vasa efferentia through the rete testis. The vasa efferentia leave the testis and open into the epididymis located along the posterior surface of each testis. The epididymis leads to vas deferens that ascend to the abdomen and loop over the urinary bladder. It receives a duct from the seminal vesicle and opens into the urethra as the ejaculatory duct.

Therefore, if for some reason, the vasa efferentia in the human reproductive system gets blocked, the gametes will not be transported from the testes to the epididymis.

Hence, the correct answer is option 1) testes to epididymis

Q3. Seminal plasma, the fluid part of semen, is contributed by.

i. Seminal vesicle
ii. Prostate gland
iii. Urethra
iv. Bulbourethral gland

Option 1: i and ii

Option 2: i, ii and iv

Option 3: ii, iii and iv

Option 4: i and iv

Correct answer: (2) (i), (ii) and (iv).

Explanation:

The urethra has no contribution to seminal plasma. The urethra has no contribution to seminal plasma, as it primarily serves as a passage for urine and semen. Seminal plasma is produced by accessory glands like the seminal vesicles, prostate gland, and bulbourethral glands. These glands secrete fluids that provide nutrients, lubrication, and protection to sperm. The urethra simply acts as a conduit for semen during ejaculation. Despite its role in sperm transport, it does not add any secretions to the seminal fluid.

Hence, the correct answer is the option (2) (i), (ii) and (iv).

Recommended video on Male Sex Accessory Ducts