Fertility – The Male Reproductive system – Testosterone and survival of the fittest! Sperm the body’s gladiators.

Thanks for the feedback about the new series.  When I worked with couples who were having problems with fertility it was clear that biology lessons in school had either been forgotten or did not go into much detail on either the male or female reproductive system – human anyway – I don’t count frogs as being great test subjects.

Very often I would have a female client come to me who was doing all the right things with diet and exercise but would then tell me that her partner was three stone overweight, drank heavily and smoked.  Unfortunately it takes two reproductive systems working well to increase the chances of pregnancy.  Which is why I began seeing couples together. Healthy sperm is essential as they have a tough journey ahead of them and it is case of winner takes it all and death for the rest.  Gladitorial.

Male hormone – testosterone

Testosterone is the most important of the male sex hormones, called androgens.

It is responsible for the development of the male sexual and reproductive organs – already covered in the article on the male reproductive system.

Testosterone also stimulates the development of the secondary male sex characteristics, such as an increase in muscle mass, increased body and facial hair, enlargement of the larynx and the vocal-chord-thickening, which leads to a deepening of the voice.

There are likely to be some changes in behaviour around this time too. In some cases there will be an increase in aggressive behaviour but there is certainly much more sexual awareness as the effects of the testosterone kick in.

Although testosterone is produced in the testes its production is regulated by a complex chain of messages that begins in the hypothalamus in the brain. The hypothalamus secretes Gonadotropine-releasing hormone (GnRH) to the pituitary gland in carefully timed bursts. This triggers the release of luteinising hormone (LH) which in turn stimulates the Leydig cells of the testes to produce testosterone.

At puberty the production of testosterone increases very rapidly and declines equally rapidly after the age of 50. This change in testosterone levels is one of the reasons that it is quite likely that men will suffer some form of menopause and need to ensure that their diet reflects the reduction in this bone and muscle-protecting hormone. It is also possible that, as in women, the sexual hormones also help protect the body against a number of other diseases such as heart disease and cancers.

The testes produce between 4-7 mg of testosterone per day but – like the two female hormones oestrogen and progesterone – this decreases naturally with age. There are rare cases where young boys fail to develop at puberty, causing problems with bone and muscle development and underdeveloped sexual organs. The likely cause is damage to the hypothalamus, pituitary gland or the testes themselves.

There is also the effect of medications such as statins over prescribed to reduce cholesterol. Whilst LDL (low density lipoprotein) is unhealthy, particularly if oxidised which results in clumps forming in arteries, cholesterol is a vital component in the production of hormones. This is why one of the side effects is sexual dysfunction. The problem however with elevated LDL is that it can caused blocked arteries everywhere in the body including in the groin. This is where diet and lifestyle changes are so important.


Sperm and the fertilisation process

I shall cover the female reproductive system separately. However, one of the key messages is that lifestyle and diet have an effect on both the development of the reproductive organs and the health of the system in general for both men and women alike.

Fertilisation of a woman’s egg could not take place without sperm. The Sperm is a reproductive cell, which only has one purpose for its existence and that is to fertilise an egg produced by the female.

Each sperm is approximately 0.05 mm in length and looks like a tadpole. There are three main sections including a head, middle and tail and each plays a role in propelling the sperm up through the vagina and into the fallopian tubes to achieve successful penetration of the egg.

The acrosome at the front of the head contains special enzymes designed to help the sperm penetrate the walls of the egg. The middle section contains mitochondria which supply the enormous energy required by the sperm to travel the distance it has to and the tail is the propeller that produces a speed of 3.5 mm per minute.

Inside the sperm are the essential genetic materials called chromosomes necessary to determine the sex of the foetus and the paternal inherited characteristics.

The production of sperm

The successful production of sperm is dependent on a number of factors but particularly temperature. The testes need to be 3 degrees Centigrade cooler than the rest of the body, which is why the testes are outside the body in the scrotum. So if you are male and commute every day with your laptop strategically placed you may be raising the temperature in your testicles too high!

Around 10 to 30 billion sperm are produced each month in the seminiferous tubules in the testes and they then pass into the epididymis, for around 72 hours, where they will mature. The epididymis takes around two days to fill completely and if there is no ejaculation the sperm disintegrate and are re absorbed into the body.

The sperm’s role in fertilisation

Following ejaculation into the vagina the millions of sperm that have been released are propelled upwards into the womb where they are welcomed with a bath in an alkaline mucous in the cervical canal. This nourishes them and gives them the strength to make the tough 20 cm, 45-minute journey up into the fallopian tubes – although there is a huge mortality rate reducing the numbers to approximately 2,000 sperm. Once in the fallopian tubes the sperm can stay alive for around three days as they wait for an egg to be released from the ovaries. If an egg is already there then the survivors will attempt to penetrate its resilient walls.

The special enzymes in the head of the sperm cause the surface of the egg to liquefy allowing it to enter. Obviously it would be devastating if all 2000 sperm penetrated the egg so as soon as one makes it through all the other sperm give up and die.

The sperm sheds its tail as it no longer needs propulsion and it then fuses with the egg to form a nucleus which then begins to divide into two cells. Over the next 72 hours the egg will continue to divide until a 64-celled egg is produced.

So the production of billions of sperm results in the fittest and healthiest achieving fertilisation with the egg and the development of the life support system for the next generation.

Diet and lifestyle are extremely important in the health of the sperm and there are a number of factors that will affect the numbers produced, motility and the successful fertilisation of the egg.

Next time a look at some of the disorders of the male reproductive system.


©Sally Cronin- Just Food for Health 2009 and Forget the Viagra… Pass me a Carrot 2013.

The first part of this series on fertility can be found here.


The correct place for your laptop!