The egg cell is 20-25 cm. from the place where the sperm enters the female body. This distance is about 3000 times the size of the sperm. Considered in proportion to its own size, this distance is quite large and to traverse it the sperm needs strong support.
Before the egg can meet the sperm, some preparations begin in both the male and the female body. The great majority of these preparations are to protect the sperm on its journey in the mother's body. For example, in the uterus various contractions and undulations occur. This uncommon activity in the uterus and fallopian tubes facilitates the sperm's advance towards the egg. The interesting thing about these contractions is the substance that causes them. This substance is called prostaglandin and is found in the seminal vesicle fluid that comes with the sperm from the male body. Despite the fact that it comes from a different body, this substance knows the structure of the mother's uterus and affects it in such a way as to make the way easier for the sperm.16
In order for fertilisation to take place, the changes that take place in the uterus are not limited to these. During this period the tubes expand; under the influence of the oestrogen hormones, the mucous membrane that lines the uterus increases in size and weight. The epithelial cells membranous tissues composed of one or more layers of cells separated by very little intercellular substance proliferate. This structure in the mucous assumes a shape that will permit the sperm to pass through these spaces with the movement of its tail. Besides allowing the sperm to move easily, this transformation has another very important function: the tissues serve as a storage and filter area, allowing only normal sperm to pass. Sometimes the sperm do not have a shape that can ensure fertilisation. In this case, they are suspended in these tissues.
As can be seen from the foregoing, it is evident that every movement in the uterus and ovaries is specially designed for the sperm to reach the egg cell. For example, after ovulation has occurred and the possibility for an egg to meet a sperm has been ensured, the mucous begins to perform a reverse operation: it becomes thick and dense, preventing the sperm from entering.
The reason for the changes that happen in the female reproductive system is to allow the sperm which enter the body to reach the egg (ovum). But, as we saw above and in the previous section, this is a matter of great interest: the elements in the female reproductive system assist cells coming from a totally different body.
How can it be that a cell has come to have so much detailed information about other cells with which it has never even shared the same environment? (even if they had shared the same environment the result would not be different.) How does it know, for example, that the movement of these cells must be facilitated? Indeed, it is not possible for the cells that produce the fluid in the uterus to know the qualities possessed by sperm or to prepare a suitable environment for them.
All the functions we have described up to this point occur in all women in the same perfect sequence. When we consider the operation of these harmonious and complementary systems, we come face to face with an evident plan and design: the sperm is designed for the mother's body; the mother's reproductive organs are especially ordered to accommodate the sperm. If there is the slightest defect in this harmony, for example, if the sperm does not have the tail that allows it to move, or if it lacked the fluid to balance the acidic environment in the mother's body, reproduction will not occur.
This clearly shows that the great harmony that exists between the male and female reproductive cells is the work of a deliberate and planned creation. It is Almighty God, the Lord of the universe Who has created mankind from a drop of fluid, male and female, in harmony with each other. Human beings should consider the perfection of God's creation and submit themselves unconditionally to Him, bowing before the eternal power of the Lord.
And in your creation and all the creatures He has spread about,
there are Signs for true believers.
(Qur'an, 45: 4)