In the preceding section we spoke about the role of the Sertoli cells in the transformation of the spermatids into the sperm. What is the physical force that activates these cells and makes them know their duty to nourish the spermatids and monitor their development?
The impetus which makes the Sertoli cells perform their function comes from the follicle-stimulating hormone (FSH), which was mentioned in the earlier section. This hormone is secreted from the anterior pituitary gland and stimulates the Sertoli cells. If this hormone is not produced or fails to reach the relevant area, sperm cannot be produced. When the Sertoli cells receive the stimulation, they begin to secrete a hormone called oestrogen, which is indispensable for sperm production. Another kind of cell that influences sperm production is called the "Leydig" cell; it is found between the seminiferous tubules. These cells produce another hormone required for sperm to develop. The LH (luteinizing hormone) is secreted from the anterior pituitary gland and stimulates the Leydig cells. Then, these cells begin to produce the testosterone hormone. Testosterone is the hormone which assures the growth of the reproductive organs, the development of various glands of these organs and the development of the male sexual characteristics; it is, moreover, the most important hormone in the production of sperm.
The Sertoli cells have additional functions such as protein production. This protein will carry the oestrogen and testosterone hormones to a fluid found in the seminiferous tubules.6
And the Leydig cells also have a second function. In order for the sperm cells to move, they require energy; the Leydig cells supply this energy by the fructose they produce. (This important topic will be dealt with in more detail later.)
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Left: Development stages of the sperm in the seminiferous tubule are as illustrated above. Seminiferous tubules are lined with sperm-forming cells (spermatogonia) in various stages of development. Through the process of division, these cells form the cells called "spermatid". At the final stage of these processes, the head and the tail sections of the sperm are formed. After all these complex processes, the development of the male reproductive cells, where the information relevant to the human being is stored, is completed.
Right: In the production of sperm, several interrelated systems go into operation in the testes. At the side you see a section of the intricate interior structure of a testis. Over and above the complex structure of the human body there is a flawless interrelation between its organs and cells. The functions of the body are carried out thanks to this interrelation. Only one single part of this system made ready for the production of a sperm is enough for us to understand the perfection of the body's structure.
As we can see, as in other parts of the body, the hormonal system also performs in a perfectly organized fashion in the reproductive system. Every hormone immediately understands the message carried by another and responds as required. For example, the pituitary gland, when it knows the time is right, goes into action and sends commands to various cells in the testes informing them of the job they must do in the organs and tissues. Moreover, what stimulates the pituitary gland into activity is a different area of the brain called the hypothalamus.
The first stage of the formation of a human being is concerned with the correct understanding of the messages hormones carry and with the proper execution of the commands. How do cells and molecules discern and react to messages carried by hormones? How do they know the chemical make-up of each one and what methods must be employed to affect them?
The fact that, in order to support the production of sperm, the Sertoli and Leydig cells go into action at the command of the pituitary gland (a gland very distant from them, which they have never seen and which has a totally different structure from their own) combined with the fact these cells would not perform any function at all without these commands, makes it impossible to explain their activity in terms of chance. It is impossible that hormones have gained their special characteristics as a result of a series of chance occurrences, because a severance or an interruption during one stage of the system will influence a whole chain of processes. If one element in the system is defective, the functioning of the whole system is impaired. For example, if the Sertoli cell does not know the meaning of the FSH hormone sent by the pituitary gland and does not begin to secrete oestrogen, sperm cannot be produced. Or, if the Leydig cells cannot perform their function to provide fructose, or if they produce it in insufficient quantities, a sperm, even if it is mature in every way, will die after entering the mother's uterus because it cannot find nourishment; and because it cannot reach the egg, fertilisation will not occur.
This situation shows us a clear reality. The One Who has established the connections between the organs and the cells is God. He has inspired the pituitary gland, the hypothalamus, the Leydig and Sertoli cells, in short, every element involved in the process, to act in a way that will assure the production of sperm in the male body. He gives them the ability to understand each other's language. Everything happens according to God's command. As we read in the Qur'an:Egg,
He governs all, from heaven to earth... (Qur'an, 32: 5)