The penis and the scrotal pouch (Latin: scrotum), holding the testicles (balls, eggs (Ger.)), together constitute a token that characterizes the male human. The word testicle does have something in common with the word testament. The Latin word testis also means witness; in Roman days, someone without testicles was definitively not a man and could therefore not testify.

The scrotal pouch is in fact a relatively simple pouch, made of rather thin skin, but with a definite muscle sheet underneath – that is the reason why, if necessary, the scrotal pouch can make itself somewhat smaller. Inside, the pouch is divided into two smaller pouches, each containing one testicle with its epididymis. An epididymis is connected to the testicle and overlies it like a cap; it contains a very large amount of microscopically small tubes. From the epididymis, the vas deferens will conduct the freshly made sperm cells to the area of the prostate. The vas deferens runs together with blood vessels that supply blood to and from the testicle and some muscle fibers; as a sort of long thin sausage they perforate the abdominal wall at the groin.

Since, from the standpoint of the abdomen, the testicles are located ‘outside’ the body, there must be a tiny hole in the abdominal wall there to let the vas deferens in: early, or later in life, a hernia may form at this weak spot. Right behind the prostate the vas deferens joins the outlets of the seminal vesicles to be able to leave the body through the urethra as semen, in search of a female egg cell.


Like so many other organs in our body, the testicle has its identical counterpart – one never knows, mother nature must have thought. The left and right testicle (plus everything that goes with it) have exactly the same function. Unlike what some people think, nothing is held in reserve; both testicles are active, although, in normal circumstances, one testicle is suffi cient.
The testicles have two functions:

  • The production of testosterone, the male sex hormone. A hormone is a substance, a molecule, that acts as a messenger in the blood. Since the blood flows through the entire body, the hormone in it will also reach every spot in the body; some organs, that are susceptible to the hormone, will then be told to do something. Testosterone will cause a boy to change into a man during puberty: he will grow a beard, his voice will get a lower pitch, his penis will grow, he will be able to have erections and will develop feelings of (male) lust. Of course, it is clear at a younger age that the child is a boy and not a girl (that difference is coded into the genes), but only after puberty started off – in girls usually somewhat earlier than in boys -, the hormone production is increased and male characteristics enhanced. Later in life, the hormone production will remain relatively constant, although it wears off at old age. Despite a lot of positive effects of testosterone, there also exist negative ones: it causes baldness in some men and may lead to growth of the prostate and may play a role in the develop ment of prostate cancer. The level of testosterone in the blood varies from day to day and from one man to another. A higher testosterone level does not cause more feelings of lust, nor a bigger penis, nor a higher chance to develop can cer.
    Hormones are usually needed in very small quantities – testosterone is no exception; without too much problems, one testicle can be missed – the other will produce sufficient amount of testosterone.
    There exist, however, other male sex hormones in the body, which play a lesser role; these hormones are made in the adrenals, which also produce – in males too – female sex hormones.
  • Other cells inside the testicle are responsible for the production of sperm cells, millions each day. Production od sperm cells will continue day and night, so not only during ejaculation. The sperm cells can, however, be temporarily stored behind the prostate in the seminal vesicles. Sperm cells will last a long time; most cells in the semen are some two months old. After ejaculation, it takes about three days to get the semen back to normal (numbers of sperm cells) again.
    Sperm cells are self-supporting and have their own engine in the form of a twisting tail. In the head of the sperm cell half of the total amount of genetic information needed to build a complete human is stored; the other half is supplied by the female egg cell. The production of sperm cells is ‘on full ahead’ all day long, while one cc of semen can easily contain 40 million sperm cells or more. Quality control is something to be desired, however, since about half the amount of sperm cells are not built well or malfunction; obviously, mother nature thinks that quantity is more important than quality – only one sperm cell is needed to mix with the female egg cell.
    After a sperm cell ha been made in the testicle, it will need to grow into an adult cell, capable of fertilizing the egg cell; this maturation process takes place in the labyrinthine tube system of the epididymis. Harboring the maturation process of the immature sperm cell is the only function of the epididymis. When the sperm cell has grown up, it is further transported through the vas deferens in the direction of the prostate.

Beneath the skin of the scrotal pouch and in the stem that contains the vas deferens and blood vessels towards the testicle a lot of tiny muscle fibers can be found. If the testicles (and with it, fertility) are in danger, for example in extreme cold, but also in fright, these muscles come into play and contract; this causes the scrotal skin to ripple and get thicker, while the testicles are pulled up close to the warm and protecting body.

It is still not clear why mother nature has placed the vulnerable testicles more or less outside the protective body. Probably it has something to do with the production of sperm cells, which is perhaps more efficient while the temperature in the testicles is a bit lower than 37 degrees Celsius.

Diseases, signs and symptoms

Diseases of the testicles can be divided into several categories:

  • Inborn errors:
    • In cryptorchism, the testicle is not located at its right place in the scrotal pouch. Right after conception, when we people are just starting off, a lot of thing are going on a clump of cells that later becomes our body. Organs are made, relocated, made smaller or larger, or can disappear again. At first, the testicles are located at a spot in our future body where, in adult life, our kidneys will be; in order to get into their right place in the scrotal pouch, they will have to move ‘downwards’. Sometimes something goes wrong and one or both testicles end up somewhere else in the body – its gets stuck somewhere on its way down. Usually, if it does get stuck, it can be found in the groin (almost there), but in some cases it is still inside the abdomen. In all of these cases of cryptorchism it is necessary to correct this surgically at a young age to prevent malfunction of the testicle at a later age.
  • A hernia in a child is always inborn, i.e. it was already there at birth. On its way from the ‘kidney region’ towards the scrotal pouch (see above), the testicle will need to pass the abdominal wall at the groin. Long before birth, a small hole is formed there to let the testicle pass. After passage, this hole is supposed to get smaller again, so that it is just big enough for the vas deferens and some blood vessels. Sometimes, however, this opening is left too big, so some of the inner lining of the abdomen can bulge out once the pressure inside get higher after birth (for example by crying). This is called a hernia. Since this can also be considered a disorder in the ‘lowering’ of the testicle, a hernia in a child is often associated with cryptorchism.
  • Diseases of the epididymis:
    • An infection of the epididymis is often associa ted with an infection of the prostate. Between epididymis an prostate a connection exists in the form of the vas deferens, which contains sperm cells, but also nutrition for them. Bacteria like this food too and can easily creep up from the prostate to the epididymis. An infection of the epididymis is rather painful and can lead to general sickness and fever. It can cause scar tissue to form and obstructions of the tubes inside, which in turn can lead to a decrease of fertility. Also a cyst, a small cavity filled with liquid, may form in the epididymis; this complication is called a spermatocele, which can cause irritation if it gets large enough. Different types of bacteria may play a role in these infections; venereal diseases, like gonorrhoea, may sometimes cause violent infections of the epididymis.
  • An obstruction of the tiny tubes inside the epididymis may block the passage of sperm cells that maturate there. The result is a decrease in the number of sperm cells that eventually reach the prostate and , therefore, lower sperm counts in the semen and a decrease in fertility, although, in normal circumstances, the other testicle/epididymis should be able to produce enough sperm cells to ensure normal fertility.
  • spermatocele is a (usually) small cavity, filled with watery liquid, in the epididymis. A lot of men have one or more small spermatoceles in one or both epididymis, probably the result of infection(s) long ago, which often go virtually unnoticed. Usually, a spermatocele does not cause pain or discomfort, unless it becomes very large, in which case it may cause irritation because it is ‘in the way’. Sometimes they may reach several inches in diameter and cause irritation while walking. However, spermatoceles mostly remain small and never give any trouble; since spermatoceles are quite harmless and almost never give rise to complications, it is best to leave them alone and avoid therapy that does.
  • Diseases of the testicle:
    • A small testicle may be inborn, i.e. present at birth, or caused later in life, for example by infections. Usually, an infection only affects the epididymis. Mumps, if caught in adolescence, may, however, cause infection of the testicle itself. Fortunately, this complication is seldomly seen nowadays. An infection of the testicle can cause problems regarding to the production of sperm cells and may, if both testicles are infected, lead to infertility. In that case the affected testicle will become smaller. The hormone production is usually less affected.
      An accident may also cause damage to the testicle and the formation of scar tissue, while a testicle that is not in its right place, i.e. in the scrotal pouch, does not develop well and will grow insufficiently during puberty.
  • Cancer of the testicle is, fortunately, a rather rare disease. Unfortunately, it usually strikes young men between 16 and 30 years of age, although it is sometimes seen in elderly men. It is also an aggressive cancer, which grows quickly and spreads early an easy, which makes treatment difficult and time-consuming. A lot of young men have an enormous sense of shame about problems in this area of the body and fail to go to the doctor quickly; since the tumor is usually painless, they often think that it is not serious or, even, that they have picked up a venereal disease. All of the above often leads to a late visit to the doctor and a late start of therapy.
    A tumor (cancer) of the testicle often shows itself by a fast enlargement of the testicle. Usually, lumps or nodule can not be detected and it seems that the testicle as a whole has grown bigger. As a rule, it is not painful.
    Cancer of the testicle is often considered to be an inborn disease of the testicle; the tumor has been there since birth, but only becomes active during or right after puberty. This explains the youth of the patients. It also explains the fact that it happens more often when the testicle has not come down nicely in the scrotal pouch, even if this has been surgically corrected. This last fact is a good reason to search for a testicle that is not found in the scrotal pouch or groin; if it is located somewhere in the abdomen, it has a high tendency to lead to cancer, which is not detected until late in the disease, when it has already spread to other parts of the body. If one testicle has been found to contain cancer, the chance that the other will be affected too is higher.
  • hydrocele is a swelling of (part of) the scrotal pouch because of an increased amount of moist around the testicle/epididymis. Every testi cle/epididymis has its own little pouch, which contains a little bit of moisture, so the testicle can move around a bit. Several causes, including inborn ones, may lead to an increase of the amount of liquid, causing the scrotal pouch to bulge. This condition is harmless, but may cause irritation when the bulge becomes too big. There is no cancer involved and it does not lead to cancer either.
  • Infertility may have several causes:
    • The production of sperm cells is too low or non-existent. This may be inborn, like in cryptorchism or caused by hormonal disorders; in these cases the testicle is usually small. It may also have been developed at a later date, for example by an infection with mumps (not in childhood).
      Of course, in order to lead to a diminished fertility it is necessary that the other testicle is insufficient too, since one normal testi cle/epididymis should be enough for normal fertility.
  • An obstruction further along the way; the sperm cells are produced in normal numbers but the exits are blocked. The obstruction is often located at the level of the epididy mis, for example due to an infection, but a block may also exist in the vas deferens. Sometimes, this is meant to be, like in sterilization, but it may also be inborn. An obstruction may also exist at the level of the prostate.
  • Because of an infection of the epididymis the maturation of the young sperm cells may be hampered, which leads to a loss of quality and ‘effectiveness’ of the semen, although a normal number of sperm cells exist.
  • varicocele is a disorder of the small veins, that run the blood from the testicle back towards the heart. Usually there are one or two big blood vessels, collecting the blood from the small network around the epididymis and vas deferens, and running upwards to connect to the bigger veins further ahead. To prevent blood flowing back towards the testicles, valves are inserted into these veins, which prohibit backflow. Sometimes, these valves are malfunctioning, causing backflow (especially in the upright position, helped by gravity, and during exercise) and subsequent enlargement of the small vessel network in the scrotal sack. This phenomenon feels like “a bag of worms”. Since the malfunctioning veins are almost trice as long at the left side than at the right, varicocele is almost unvariably leftsided. Malfunction of the valves is usually inborn, but does not show until puberty or later, when the testicles are matured. The disease may give rise to dull pain, especially during exercise. There is still debate whether it may constitute a reason for decreased fertility. On the one hand, some cases of diminished fertility have improved after therapy, although many have not. On the other hand, many men have varicocele without knowing and without fertility problems, while one normal testicle (on the other unaffected side) should be enough to preserve normal fertility. In many cases of decreased fertility, the cause is unknown, so, when the patient is found to have varicocele, the fertility problem is linked to this for lack of another possible cause.


There is not a large number of tests available for the scrotal pouch.

  • The physical examination (the look and feel) of the scrotal pouch usually gives a lot of information about it. It is easily shown whether the testicles are at their right location in the pouch, if they are to big or too small, or painful. The presence or absence of a hydrocele, spermatocele or hernia can be checked. Cancer of the testicle can usually be ruled out, although the physical examination is not always conclusive. If an infection of the epididymis is present, the epididymis is usually painful; it may sometimes be a sign of a concurrent prostatitis. The vas deferens can usually be felt and checked quite easy.
  • Blood samples are useful to detect the level of testosterone (the male sex hormone) and may have its use to measure certain substance in relation with cancer of the testicle.
  • Urine examination can be important to exclude an infection of the bladder, prostate or epididymis. In a number of cases it will be necessary to use a cotton stick to ‘scrape’ some material (cells, bacteria) from the urethra, to be further examined in the lab. In this way, Gonorrhoea or Chlamydia infections can be checked.
  • Semen examination will show the number and quality (motility) of the sperm cells, for example in case of infertility. In normal circumstan ces, millions of sperm cells are produced each day, but not all of them are of good quality; mother nature relies on the ‘law of large numbers’ to ensure pregnancies. There are big differences in the number of sperm cells per cc. from day to day and from one man to another (between 20 and 80 million per cc.) while a large number of sperm cells does not equal a high fertility – if only because a high fertility needs two people. About 50-70% of all sperm cells are active and (as far as we can tell) healthy.
    The number of white blood cells (=inflammation cells) can also be counted in semen and a culture can be done to confirm an infection.
  • Using ultrasound (like SONAR in a submarine) an image of the inside of the scrotal pouch and its contents can be made. The examination is painless. Using this technique it is possible to get an impression of the extent of cancer of the testicle and the presence or absence of a hydrocele or spermatocele can be confirmed.
  • In some cases, for example in case of infertility, it may be necessary to take a tissue sample (biopsy) of one or both testicles in order to get information about the quality of sperm cell production; this examination is usually done under general anaesthesia.


It is impossible to present all possible therapeutic options for all diseases of the testicles. More frequent forms of treatment will be mentioned.

  • Treatment of an infection of the epididymis depends of course on the cause, i.e. the type of bacteria involved. For an ‘ordinary’ infection other kind of antibiotics are needed than for a venereal disease like gonorrhoea. Also, the question whether there is another infection present, like an infection of the prostate, needs to be answered; if present, this needs to be treated too.
  • hydrocele or spermatocele only needs to be treated surgically if it causes discomfort or pain, usually because of its size. In the past, a common practice was to empty the ‘cele’ by puncturing it with a needle and drawing out the liquid with a syringe, but it often resulted in only a few days of relief, since the ‘cele’ quickly filled with liquid again. Together with the needle, sometimes bacteria entered into the formerly sterile environment of the ‘cele’ and caused infection.
  • Cancer of the testicle needs to be treated as soon as possible, since the tumor grows very quickly and spreads early and easily to lymph nodes and other organs like the lungs or the abdomen. Treatment consists of removal of the testicle, while often a tissue sample is taken of the other testicle to make sure that there are no cancer cells there. If spreading of the disease has already occurred, than additional therapy is often necessary, like radiotherapy or medicine to destroy all other cancer cells. Fortunately, the success rate of treatment has gone up in the past years, even in advanced (spread) forms of cancer. Unfortunately, a lot of patients wait a long time before going to the doctor, so the disease has already spread. Because of the young age of most patients and the aggressiveness of the therapy needed, there is a risk of infertility, necessitating semen preservation before treatment (if there is still time).
  • Infertility has many possible causes and, therefore, several possible therapies. If an obstruction of the vas deferens exists, which needs to be treated surgically. An obstruction at the level of the epididymis can sometimes be bypassed. Fortunately, it is nowadays possible to artificially fertilize the female egg cell with only a few sperm cells; even one is now enough. Infertility may also be caused by an infection, for example of the epididymis, which then needs to be treated.
  • Fertility can sometimes also be a problem. Especially when the family is ‘complete’ and there is no wish for further pregnancies. In that case, sterilization may be an option if a definitive answer is sought. The procedure is far more simple in male than it is in females and causes less complications. Under local anaesthesia two small cuts are made in the skin of the scrotal pouch, both vas deferens are cut and the end tied. The drawing shows three examples; several techniques exist with equal results – the choice depends on the personal preference of the urologist. Sometimes the ends of the cut vas deferens are tied back, sometimes a piece of vas deferens is taken out, sometimes the vas deferens is merely tied. The result is the same; near definite infertility. The procedure seldomly causes any complications.
    Sometimes, for example in a new relationship, the want for children reappears; the results of a reversal operation are, unfortunately, rather disappointing.
  • Varicocele is usually left-sided. In case of pain, attributable to the varicocele, therapy should follow. Sometimes, therapy is instituted in case of decreased fertility, where varicocele remains the only possible cause. Therapy consists of blocking backflow from the bigger veins downstream. This can be accomplished in three ways: plugging the vein(s) using a small catheter which is passed upstream from even bigger veins as far as possible and ‘glueing’ the vein shut. A more conventional way is to operate, using a small incision, and cutting/tying the vein. A third method is laparoscopy: using a small tube, with lenses, the abdomen is entered and the vein(s) tied shut using small metal clips. After therapy, other blood vessels will take over. All three methods are reasonable safe in experienced hands and the results are about equal; the choice depends on the experience of the urologist with a given method. The overall outcome is lowering of the blood pressure on the small vessels in the scrotum, which has almost instant effect on the pain, if present, while a possible effect on fertility, if any, may take several months. The small vessels will, however, allways remain somewhat enlarged due to the fact that they have been stretched too far and will probably never get as small as they once were.
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