Male Organs

The Male organs of Reproduction

A man’s sexual system is much simpler than a woman’s. Most of it’s outside (rather than inside) the pelvic cavity, and there are four main parts to it:

1. Testes (testicles) held in scrotal sacs.
2. Genital ducts.
3. Accessory glands.
4. The penis.

Fig 1: The male reproductive system ⁱ

The testes 

The testes (testicles) are where sperm and important sex hormones are made:
Anatomy of a testesⁱⁱ

• Each testis is made up of about 250 compartments called ‘testicular lobules’. Each lobule has 1 to 4 ‘seminiferous tubules’, which measure up to 2 feet (60cm) long.
• The seminiferous tubules are where the head section of sperm are formed, with the support of ‘Sertoli’ and ‘Leydig’ cells.
• The Leydig cells produce testosterone and other androgen hormones.
• The Sertoli cells “grow” sperm, and each Sertoli cell can only support a fixed number of sperm at a time.
• The Sertoli cells start developing when the baby boy is in the womb (when their numbers are set), and they complete their development during puberty. The number of Sertoli cells naturally decreases with age. However, exposure to external estrogens and estrogen-like substances in foods, drinks, and wider environments accelerate their decline.
• These factors combine to reduce the number of Sertoli cells, which directly impacts a man’s fertility. ⁱⁱⁱ

The scrotal sacs help maintain the right temperature (1-2°C below the rest of the body) in the testes by raising and lowering them.

The genital ducts 

There are three sections to the genital ducts: ^iv

1. The ‘epididymis’ (A-C) is the first part of the duct, and it’s a single, narrow, tightly coiled tube around 7m (20 feet) long. This is where the sperm tails develop, and they mature.
2. The ‘vas deferens’ (D) is at the end of the epididymis and is about 30cm (1 foot) long. It has muscular walls which help propel sperm from the epididymis up to the prostate during an ejaculation.
3. The ‘ejaculatory duct‘ is the last portion of the genital duct in the prostate gland, where most of the fluid that makes up the semen is made.

The genital ducts perform three essential roles:[show_to accesslevel=”free” no_access=’

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1. They can store the sperm for up to 2-3 months.
2. During their journey along the genital ducts, the sperm mature and become more mobile.
3. They transport the sperm out of the body.

The accessory glands 

• The seminal vesicles make 60% of the semen volume. These glands supply essential elements to semen, including fructose and hormones that provide energy and encourage the sperm to function.
• The prostate gland produces 30% of the semen. The alkaline fluid prevents infections and buffers the acidic nature of the other fluids in the semen and vagina. When semen is too acidic, the sperm become less mobile or may die.
• Sperm are 10% of semen, which travel from the testes via the genital ducts.

The penis 

Most of the penis is formed by erectile tissue encased in fibres, with a tube (urethra) and blood vessels. The penis has two main parts: ^v

• the shaft.
• The head (glans).

The penis becomes erect when the blood to it increases to swell the erectile tissue. For the penis to stay hard, the volume of blood entering it needs to be more than the amount leaving it. The hard fibres that surround the erectile tissue help the penis keep its shape and rigidity. Maintaining an erection is pretty much essential for successful intercourse and for sperm to arrive high enough in the vagina.

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