Testicles: function and characteristics

The testicles It is the most important organ of the male reproductive system since they produce sperm and male sex hormones such as testosterone, responsible for key processes in men's lives. In this article by a TEACHER we will discover the functions and characteristics of the testicles and why they have great importance in aspects that have to do with reproduction but also with other bodily functions that may surprise you.

The testes are the male gonads of mammals and form the most important part of the male reproductive system. This paired organ (right testicle and left testicle) is responsible for the production of male sex cells, sperm. Its female analog or equivalent is the ovaries (responsible for producing eggs).

The testicles lie in the perineal region, behind the base of the penis and protected within the scrotal bag. Their size varies throughout life, in boys the size of the testicles is 2 to 3 cm in length, at puberty they grow to reach between 4 and 8 cm in length and 2 and 4 cm in width; Normally, the testicle remains that size although there is sometimes a slight shrinkage in old age or a slight increase in size due to the use of steroids.

As we have already mentioned, the main function of the testicles is to sperm production. Sperm are produced in the testes, specifically in the testicular epididymis, through a series of processes called spermatogenesis. Unlike eggs, sperm do not have their own reserve material, so there are cells in the testes responsible for nourishing the sperm. These cells are called Sertoli cells and it is said that they are the cells of nutrition and support of the spermatozoa since they are in charge of carrying nutrients to the spermatozoa and eliminating the waste products that they produce.

Another important function of the testicles is androgen production. Androgens are a series of hormones (testosterone, androsterone and androstenedione) responsible for the development of sexual characteristics primary and secondary males (sperm production, appearance of more body and facial hair, male sexual behavior, etc). Hormones are produced by cells called Leydig cells in response to signals produced in the brain by the pituitary or pituitary gland. This function is very important since one of the functions of testosterone is to trigger the maturation of the testes and the production of sperm. Without testosterone, no spermatogenesis occurs.

Other important functions of the testicles

Once sperm are produced, the testicle has to also protective functions. On the one hand, protect sperm from heat: In order for sperm to mature and be properly preserved, they have to be at a temperature approximately 1.3 degrees lower than the rest of the body. The testicles are suspended, outside the body, by the scrotal bag that has a muscular mechanism that reacts to a rise in temperature. When the temperature rises, the muscles of the scrotal bag relax, it is lowered, separating from the body and causing the temperature of the testicle to drop. On the other hand, when the temperature drops, the muscles of the scrotal bag contract, the bag rises and the testicles approach the male body, raising the temperature of the testicle. In addition to these mechanisms, the testes have their own arterial and venous system that is regulated according to temperature; the arterial system is responsible for raising the temperature and the venous system for lowering it when necessary.

Finally, the testicles also have immune function. Like the brain, the testicles have a special barrier, which isolates them from the rest of the body and filters out all the substances that try to enter these organs. In the case of the testicles, this is called blood-testicular barrier. This barrier is formed by Sertoli cells special, which specifically select which substances pass from the blood, preventing microorganisms from attacking the sperm.

To carry out their functions, the testicles have had to develop some very special characteristics and properties. The main characteristics of the testicles They are:

• The testicles are covered by a series of layers of muscles and skin called scrotum or scrotal bag. As we have already mentioned, the scrotum has two methods (one muscular and the other circulatory) to regulate the temperature of the testicles by moving them closer to or further away from the body. In addition, the scrotum lacks fat to cover and isolate it.
• The testicles are of a characteristic bluish white color although sometimes they can be red when they are full of blood. This coloration is due to the bags that surround them.
• The testicles originate inside the abdominal cavity, to the right and left of the lumbar spine, next to the kidneys. By the third month of fetal development, the testes leave this region and descend through the inguinal canal, dragging with it the bags that surround them to their final position forming the scrotum. Sometimes there is an incomplete descent of the testicle, especially the left one; This condition is called cryptorchidism and it can hinder fertility.
• The testicle begins to be hormonally active from the eighth week of gestation. At that time, the Sertoli cells produce an inhibitory substance of the Müllerian ducts (structure of the female reproductive system). The complete development of the external genitalia occurs between week 10 and 15 of gestation, when testosterone begins to be produced.

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