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Understanding the Male Reproductive System

In order to conceive a baby, both the male and female reproductive systems must be functioning.
For men, this means:

  • The testes must be producing normal healthy sperm, as well as male hormone (testosterone),
  • The sperm that are produced have good morphology (i.e., are properly shaped), motility (i.e., are able to move rapidly), and can accurately navigate the fallopian tubes to locate and fertilise the egg.
  • The ability to achieve and maintain an erection, and engage in sexual intercourse,
  • Normal ejaculation. This occurs when semen moves along the man’s urethra and into the woman’s vagina.

Male Reproductive System - Review

Female Reproductive System

Testes

The testes are two glandular organs, suspended in the scrotum. They are responsible for:

  • making testosterone, and
  • generating sperm.

The testes are suspended by the spermatic cords, and they contain coiled masses of tiny tubes called seminiferous tubules, which are responsible for producing sperm cells.

Epididymis

The epididymis is a single, narrow, tightly coiled tube which connects the testes to the vas deferens. It can reach 6-7 meters in length in humans! The epididymis is responsible for the transport, storage, and maturity of the sperm after the testes produce them. Sperm that emerge from the testes are actually immature and not capable of fertilisation.

Vas Deferens

The vas deferens is a long muscular tube that connects the left and right epididymis to the ejaculatory ducts. It is responsible for moving sperm from the epididymis into the pelvic cavity, to just behind the bladder. During ejaculation, the smooth muscle in the wall of the vas deferens contracts, pushing the mature sperm toward the penis and into the urethra.

Urethra

The urethra carries urine from the bladder to the outside of the body. It a 20 cm tube that also functions to ejaculate semen when a man reaches orgasm. Fortunately, the flow of urine is blocked from the urethra when the penis is erect, allowing only semen to be ejaculated at orgasm.

Accessory Glands

There are a number of male accessory glands. These are:

  • Seminal vesicles. Their function is to secrete a significant proportion of the fluid that ultimately becomes semen. They are located within the pelvis.
  • Prostate gland. This gland secretes a slightly alkaline fluid, which makes up between 50 and 75% of the total semen volume. It is usually milky or white in appearance..
  • Bulbourethral glands. During sexual arousal, these glands produce a clear, salty, viscous secretion (i.e., pre-ejaculate). The purpose of this is to help lubricate the urethra for sperm to pass through. It also serves to neutralise any traces of urine in the urethra, removing residual urine and foreign matter.

What is Semen and what is Sperm?

Semen

Semen is the fluid produced in the male reproductive tract that dilutes the concentrated sperm at ejaculation. Semen contains other factors produced by various male glands (e.g. the bulbourethral glands, the prostate gland, and the seminal vesicles). These additions bathe and nourish the sperm to keep it viable.

Sperm

We all know it takes sperm from the male to bind with and fertilise a women’s egg to produce an embryo.
The sperm cell (actually called “spermatozoa”) consists of a head, mid-piece and tail. The genetic material (i.e., the chromosomes) is contained in the head. It is commonly understood that when the sperm chromosomes bind with the egg chromosomes, the resulting offspring’s characteristics are already determined. Sperm also carry the all-important sex chromosome (i.e., the “X” or the “Y” chromosome) that will determine the sex of the resulting child.
The tail enables the sperm cell to move and travel to, and then penetrate the egg.
Sperm cells can survive in the female reproductive tract for up to three days.

What is Semen Analysis?

Semen Analysis is an important part of the overall process of fertility investigations. It evaluates the amount and quality of a man’s semen and sperm in order to determine male fertility.

A Semen Analysis typically assesses the following factors:

  • Total volume of ejaculate,
  • Sperm count,
  • Sperm motility (i.e., movement),
  • Sperm morphology (i.e., shape), and
  • The pH of semen and the sperm it contains.

Semen Analysis can give an indication of how successful the sperm may be at fertilising an egg, and what fertility treatments your specialist may recommend, based on your individual circumstances and the diagnosis.

The World Health Organisation (WHO) has set a reference guide for the standardisation of Semen Analysis worldwide.  A ‘normal’ semen sample is considered to:

  • Have a volume of greater than 1.5ml; and
  • Contain more than 15 million sperm per millilitre of semen; and
  • Demonstrate more than 50% of the sperm moving in a progressively forward motion; and
  • Exhibit normal morphology in greater than 4% of the sperm.