Nuts, sacks and balls

Have you ever wondered why testicles hang outside the body? Isn’t that a pretty dangerous place for something that is so vital and important to the continuation of life? The heart is placed inside the thoracic cavity, it is behind the ribs and breastbone. The brain is under a hard bony helmet, the skull. The woman’s ovaries are hidden and safe in the pelvis. So why are the testicles “placed in pouches” swinging apart from the body?

No one knows the ultimate truth, but several assumptions have been made why such an arrangement is particularly beneficial to the survival of the species, especially in mammals. It is known with certainty that the temperature of the testicles must be about 2 ºC cooler than the body temperature. Cool testicles work! Ideal temperature of testicles reduces genetic damage of sperm. A cool system is ideal for producing, storing and transporting sperm.

Even so, it has been found that in intercourse a sudden rise of temperature when sperm enters the uterine cavity through vagina and further into the fallopian tubes, activates sperm for fertilization.

Anatomically the testicles are designed so that it possible to maintain a cooler temperature. Testicles are surrounded by a muscle (musculus cremaster) that contracts and pulls the testicles closer to the body when the testicles are too cold. The same muscle relaxes as the temperature of the testicles rises, helping them to hang farther from the body and its heat. A large number of blood vessels just above the testicles, act as a cooling system. The blood vessel system cools the blood as it enters the body and continues its journey to the testicles. Abnormal dilation of these veins (varicocele) can interfere with this cooling system leading to an increased temperature and to nuts that are too hot.

High fever, bathing in a hot tub or sauna may raise the temperature of the testicles. There are many other factors that can rise testicular temperature momentarily or permanently. Overweight, lack of physical activity, sitting work, and driving for more than two hours have been shown to cause a significant rise in testicular temperature. The laptop warms up from the bottom, so holding it in your lap while browsing, warms up the testicles. Tight boxers or tight pants do not give room for the testicles to descend and cool down…

So, is it worth in the sauna or on a long drive, to equip your groins with an ice pack? Based on the current research, there is no evidence that using cold packs decreases the harmful effect of heat for testicles and improves male fertility. So, physiologically, cool balls are the best!

Marika Mettälä, Senior Lecturer in Midwifery, TAMK

Elina Botha, Senior Lecturer in Midwifery, TAMK