Manhood

by Driel, Mels van.

  Aristotle’s ideas on spontaneous generation in insects and other invertebrates were made less plausible by the investigations of a physician at the court of Tuscany, Francesco Redi (1626–1697), which demonstrated that flies lay eggs in meat waste. The starting point for his studies was a passage of Classical poetry. In Book xix of Homer’s Iliad, Achilles is worried that the flies in the wounds of his slain friend Patroclus will produce worms. Redi examined exactly what Homer meant and observed that after a while worms (i.e. maggots) emerged from meat on which flies had settled. No worms appeared where insects had no access. He used an amazing range of different meats: ox, veni-son, buffalo, lion, tiger, dog, lamb, kid, rabbit, duck, goose, chicken, swallow, swordfish, tuna, eel, tongue, etc. The result was always the same, and he drew the conclusion that insects were not produced by rotting waste matter, but also came from eggs, which the mother laid in the meat for nutriment.

  The celebrated anatomist Frederik Ruysch (1638–1731) was equally sceptical that fertilization could take place ‘solely through the vapours and spirits of the male seed’. ‘I am well aware that in sexual congress the larger part of the seed flows away, but I am convinced that the viscous seed remaining in the womb is sufficient to bring about fertilization.’ Ruysch had found the uterine cavity and the two ‘trumpets’

  (Fallopian tubes) filled with a very large quantity of male seed. This was most unusual: Harvey had never been able to find seed in the uteri of deer, but Ruysch had found it in women. (In the 1970s Harvey’s findings were examined in the light of modern knowledge by Professor Roger Short, who also made a remarkable film replicating Harvey’s 14

  t h e t e s t i c l e s a n d t h e s c ro t u m research. In hindsight it was no wonder that Harvey did not discover how reproduction actually functioned, mainly because this is much less transparent in deer than in most other animals. And of course without a microscope it was very difficult for him to detect sperm in the uteri of the hinds he dissected shortly after mating.)

  One day Ruysch had a unique opportunity. He was commissioned by the Amsterdam municipal authorities to write a report on a murder.

  The victim was a prostitute, whose throat had been cut by a young man with whom she had just had intercourse. After establishing the cause of death, Ruysch satisfied his scientific curiosity, with three doctors in attendance. He cut open the victim’s abdomen, ‘being most curious to see what would appear in the womb and those parts made for conception. I therefore removed the womb, the Fallopian tubes and their appendages very carefully from the body,’ he noted. The cervix was closed, but when he pressed gently with his finger it opened and sperm came out. He then opened the womb and found more sperm. Both tubes were also full of it. He preserved the material in his ‘balsamic’

  fluid, which caused the sperm to harden and stabilize. Subsequently it could serve as scientific evidence.

  Later Ruysch had a further opportunity to gather first-hand evidence. This time it involved the body of a wife caught in the act with her lover and stabbed to death by her husband. Ruysch was called in to perform a post-mortem examination, and when he found the womb somewhat more ‘elevated’ than normal, he suspected that fertilization had taken place. He then removed the womb from the body for further examination, and found her lover’s sperm not only in the uterine cavity, but also in both Fallopian tubes.

  Ruysch’s assumption was that if the seed itself were not necessary to effect fertilization, the tubes would not be full of sperm. When asked, most women had told him that when they became pregnant they usually had the feeling that most of the sperm had remained in their bodies. ‘What else is one to believe than that the substances of nature, and not only their vapours or spirits are required for this work,’

  observed Ruysch. The question of whether the sperm contained tiny creatures, which also played a part, he left unresolved.

  For centuries Aristotle’s view on the predominant role of the male in reproduction obviously had a great appeal for many people, including another scientist, Antonie van Leeuwenhoek (1632–1723). Using candlelight and ground glass he had made his own microscope. He was actually a cloth merchant by trade and also ran a draper’s shop, where he sold buttons and ribbons. In the back room behind the shop he became a self-trained scientist. He taught himself glass-blowing, grinding and 15

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  polishing and was subsequently able to produce high-quality lenses.

  During his lifetime he ground over five hundred, including some with a magnification of approximately 480×. No one knows why Van Leeuwenhoek started using the microscope. Perhaps he wanted to take a close look at textiles, or he may have simply revelled in his own ingenuity and skill. His simple microscope was not much more than a wooden frame containing a small glass globe, made by extending a thin length of red-hot glass until a globule separated from it which after cooling was polished smooth. It was certainly not easy to use the apparatus. Endless peering, from very close range, and preferably in bright sunlight, soon led to tired eyes. Van Leeuwenhoek had an additional problem: he could not draw at all. For this reason he employed a number of draughtsmen, who made illustrations for him.

  A Leiden professor was very interested in the cloth merchant’s work. He introduced a relative of his, the student Johan Ham, to Van Leeuwenhoek. On his second visit, in 1677, Ham brought with him the sperm of a man with the clap. He had seen tiny creatures moving about in it and assumed that their presence was connected with the man’s disease. He asked Van Leeuwenhoek to take a look with his microscope. A few years before, at the request of a foreign scholar, Van Leeuwenhoek had put spittle, sweat and sperm under his microscope and at that time had seen something resembling tiny globules in the sperm, but had not pursued his observations because he found them distasteful. Now he was urged by the student to repeat the investigation. Van Leeuwenhoek felt extremely uncomfortable. The reason was that in his follow-up studies he used his own sperm and to avoid accusations of sinful behaviour felt obliged to explain that the observations had been carried out on sperm left over after sexual relations with his wife Cornelia. On another occasion he reported that he had placed the sperm under the microscope within ten seconds of ejaculation. His research showed that the creatures Johan Ham had seen were also found in fresh, healthy sperm. He called them spermatozoa. On the basis of ancient metaphysical writings he thought initially that he saw portions of microscopic homunculi, tiny male creatures swimming about in the seminal fluid. On 3 December 1677, not feeling entirely sure of himself, he wrote to the Royal Society in London: ‘If your Harvey and our De Graaf had seen a hundredth part of what I have seen, they would have agreed with my finding that the man’s seed forms the embryo by itself, and all the woman can contribute is to receive or nourish the male seed.’ And in so doing he in fact confirmed what the Greek playwright Aeschylus (525–456 bc) had written many centuries before: ‘The mother of what is called her child, is not its parent, but only the nurse of the young life sown in her.’

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  t h e t e s t i c l e s a n d t h e s c ro t u m Van Leeuwenhoek lived to be ninety and continued with microscopic research until his death in August 1723, fifty years after his introduction to the Royal Society by Reinier de Graaf (1641–1673).

  His daughter sent his collection of microscopes and specimens to London, where it eventually disappeared, so that only a few of his better micro scopes survive in museums, where visitors are usually more interested in the silver slides and the adjustment knob than in the most important component: the tiny glass globule that served as a lens.

  With his microscopes Van Leeuwenhoek had found the answer to the problem Harvey and Reinier de Graaf had wrestled with: semen played a direct physical role in reproduction, the reason being that sperma -

  tozoa could find their way to the womb. He had dismissed the views deriving from, for instance, the work of Redi, Jan Swammerdam (1637–1680) and De Graaf, in which the ovum played a central role in reproduction. Van Leeuwenhoek had focused on the male a
spect, while the others had had looked mainly at the female side.

  The argument on the question as to what was more important: the ovum or the spermatozoon, between ovists and animaculists (also called spermists) was not finally decided until the second half of the nineteenth century, in 1875 to be exact. In that year the German anatomist Wilhelm Hertwig (1849–1922) showed in an animal experiment that fertilization comes about through the merging of the nuclei of the ovum and the spermatozoon. The exact process was revealed only in 1944, when John Rock of Harvard University put a human ovum in a dish and added a drop of living human sperm. After placing this mixture in human blood serum, Rock was the first person to observe the division of the fertilized ovum into two, the beginning of a strange process that some nine months later results in the birth of a new human being.

  Today we know that the female ovum contains more than half the information necessary for the future human being. It provides not only 23 nuclear chromosomes to complement the 23 from the spermatozoon, but also the cytoplasmatic dna located in the mitochondria, the genes of which derive exclusively from the mother. The mitochondria are simply tiny power stations in the cell. This fact torpedoes the arrogant notion that the father is most important in reproduction. More of that anon!

  Hanging left

  As regards appearance there is great diversity in the protuberances we have given the prosaic name of scrotum. Scrotums may be large or small, long or short, smooth or wrinkled, heavily or lightly pigmented, nicely rounded or extremely asymmetrical. In fourteenth-century Europe high-ranking nobles were allowed to walk around with naked 17

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  genitals under their short tunics. Their tight-fitting short breeches were not closed at the crotch. If their private parts were not sufficiently large to dangle about alluringly, they wore a braquette, a set of simulated genitalia in leather. Later, in the fifteenth and sixteenth centuries, another ornament came into fashion, the so-called codpiece ( cod means scrotum), which was sometimes embroidered or encrusted with jewels.

  It was a final relic of the age of chivalry, and today’s double-stitched fly may be the last of the codpiece.

  The left testicle usually hangs slightly lower than the right. This has nothing to do with being left- or right-handed. The anomaly is probably due to the fact that in most men the left testicle is slightly larger and heavier than the right. As a result the penis also usually

  ‘hangs left’, as the saying goes.

  Until quite recently tailors making a bespoke suit asked their customer whether he ‘dressed left or right’, so that extra material could be sewn in to camouflage as far as possible the effect of dribbling after urination. The modern clothing industry certainly also takes this into account: the better makes of menswear cut the front of the left leg of a pair of trousers three-quarters of a centimetre wider as standard!

  Apart from that, opinions differ on whether the scrotum couldn’t have been made slightly more appealing in appearance and on whether the positioning of the scrotum couldn’t have been a little more convenient, certainly in an age when cycle sports are exceptionally popular. After all, in many animals the semen-producing organs are tucked neatly into the abdominal cavity. In rodents and prosimians, for example, the testicles descend only in the mating season and subsequently return to the abdomen. This is not the case in man or in his oldest domesticated animals. Recent research has shown that the positioning of the testicles is mainly connected with the lifestyle of the species. This actually undermines the ‘balls-as-coolbox’ theory (of which more below). Animals that move fluidly have their sperm -

  factories enclosed in their bodies, while those that run, jump, jolt and bump, were better off with testicles located externally.

  Long before birth the testicles and epididymides are formed in a place at the back of and high above the abdominal cavity, in the vicinity of the kidneys. From there the testicles descend down a kind of slide formed by the back of the bulging abdominal membrane, towards the inguinal canal at the bottom of the abdomen. If everything goes to plan in the last three months of pregnancy the testicles and accompanying seminal ducts and blood vessels descend through that inguinal canal into the scrotum. The above explanation is not totally accurate, since in fact the testicles gradually move lower and lower as the body grows lengthways. Be that as it may, in approximately 95 per cent of ‘full-18

  t h e t e s t i c l e s a n d t h e s c ro t u m term’ males the testicles are in the appointed place around the time of birth. It may happen that the testicles remain within the abdomen.

  When this occurs in a male pig the animal is known as a ‘cryptorchid boar’ or sometimes, more colloquially, a ‘rig pig’.

  A true cryptorchid boar takes at least ten minutes to complete ejaculation of his sperm – two coffee mugs full, containing as it does over 80 billion spermatozoa. In mating a zebra stallion may ejaculate as much as 300 millilitres of sperm, that is, over a quarter of a litre.

  After being mounted the mare appears to urinate, but in fact this is part of the seminal fluid flowing out of her body. A man discharges between 2 and 4 millilitres at each ejaculation. To put things in perspective, the volumes of a number of other animal species are as follows: bats 0.05, foxes 1.5, dogs 6, domesticated donkeys 50, domesticated horses 70, domesticated billy-goats 1 and turkeys 0.3 millilitres.

  The male actually owes the scrotum to his female origin. It is only at the moment when it is decided that the embryo is to continue its development as a male that the embryonic labia grow together to form the scrotum. One has only to look closely: right down the centre of the scrotum runs a line of raised skin, the scrotal seam.

  According to some experts, there is a good reason for the positioning of the testicles outside the abdominal cavity (though dissenting voices will also be heard in this book). The first group see the normal body temperature of between 36.5˚c and 37˚c as too high for the Testicular descent

  in a male foetus.

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  efficient production, maturation and storage of healthy human sperm cells. That is the principal reason why nature has opted for a location in the cool-box that we call the scrotum, where the prevailing temperature is between 33 and 34 degrees. One way in which this cool-box operates is through vascular temperature regulation: the artery supply -

  ing warm blood from the abdominal cavity is quite convoluted just above the testicles and is surrounded by a complex network of vessels called the plexus pampiniformis. This network transports cool arterial blood from the testes back towards the heart. That colder blood washes around the main artery and ensures that the arterial blood flowing to the testicles is cooled so that it cannot harm the young sperm cells. The fact that testicles need protection from both excessively high and excessively low temperatures is evident from a feature that in our modern society benefits only inveterate naturists: the strong pigmenta-tion of the skin of the scrotum. This dates from when primitive man wandered around the African savannahs without protective clothing. A dark skin after all offers more protection against sunlight than a light one. But too low a temperature is not good either! Every man who walks into the sea from a warm beach knows this: the cremaster muscles instantly lift the testes back towards the warmer groin.

  The location of the testicles outside the body was therefore pro bably designed to protect the reproductive cells from extremes of temperature. However, one further safety measure was put in place, namely the so-called blood-testicle barrier. Sperm cells are very unusual, in more than one respect. They are haploid, that is, they contain only one copy of our genetic material. All other cells are diploid, containing a copy in dupli cate of hereditary characteristics. Such diploid cells are regarded as malignant intruders in the testicles. By its own logic the immune system has an irresistible tendency to attack anything with the characteristics of a sperm cell. This is why the blood-testicle barrier, with the aid of a membrane and special Sertoli cells, seals off the sperm-producing tubes from diploid body cells.
If this line of defence is breached the man will start producing antibodies against his own spermatozoa.

  Animals

  The testicles of the blue whale are over 70 cm long and weigh about 50 kg.

  Testicle dimensions in whales vary greatly, as they do in man. Yet the sperm cells of this whale are no larger than human sperm cells. Human testicles have a combined weight of approximately 40 g, corresponding to roughly 0.06 per cent of total body weight. The testicles of a stallion weigh almost 350 g, or 0.27 per cent of its total body weight.

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  t h e t e s t i c l e s a n d t h e s c ro t u m Chimpanzees have the heaviest testicles of all anthropoid apes, with a combined weight of 119 g (0.27% of body weight), while a gorilla’s testicles are much smaller, in both relative and absolute terms (29.6 g, 0.02%). The human male is therefore somewhere in the middle.

  Species

  Weight of testicles

  Percentage

  in grams

  of body weight

  man

  40

  0.06

  chimpanzee

  118.8

  0.27

  gorilla

  29.6

  0.02

  orang-utan

  35.3

  0.05

  rhesus monkey

  46.2

  0.50

  mantle baboon

  27.1

  0.13

  rabbit

  5.5

  0.13

  golden hamster

  0.3

  0.30

  water vole

  3.8

  0.68

  wild boar

  720

  0.41

  ram (sheep)

  500

  0.63

  stallion (horse)

  340

  0.71

  There is very special sub-group among fighting cocks: they have especially large testicles, and are both ‘transvestites’ and ‘homosexual’. This type of male was discovered some years ago by a Frisian potato farmer and bird expert, Joop Jukema. The unusual creature turned out to be hard to distinguish from a female with the naked eye and displayed homosexual behaviour. The discovery was a bombshell for the biological community. The farmer christened his discovery faar, which in Frisian means patriarch. Only 1 per cent of the breed are patriarchs. It had been discovered fifty years previously that there are different types of fighting cock males: ‘basemen’, which defend a small territory against others like themselves, and ‘satellites’. The latter forage about and are tolerated by the basemen. At the time this discovery caused a sensation, but finding a third type half a century later was extraordinary.