The sperms are formed in the testicles, which in turn are created, as proved by embryology, from cells underneath the kidneys at the back and then go down to the lower abdomen at the last weeks of pregnancy.  Man’s fluid mainly contains  the following components: the sperms which should be gushing, and motile to cause fertilization and Prostaglandin which causes contractions to the uterus, thus helping the transport of sperms into the place of fertilization. The man's fluid (semen) contains also sugar  necessary for providing energy for the sperms, different fluids for neutralising the acids at the entrance of the uterus and creating a slippery environment for the easy movement of the sperms.

While hundred millions of these sperms (500 m.- 600 m.) enter through the vagina to the uterine cervix, only one sperm is able to fertilize the ovum (Fig. 2); crossing through a long distance to reach the place of fertilization in the Fallopian Uterine Tube which connects the ovary with the uterus.  The distance is full of obstacles that can be compared with the distance man takes to reach the moon!   After direct fertilization, a quick change occurs to the membrane of the ovum preventing the entrance of the rest of the sperms.

The sperm contains 23 chromosomes, of which one chromosome determines the sex of the embryo. The chromosome in the sperm is either (Y) or (X), while the chromosome in the ovum is always (X). When a sperm of the chromosome type (Y) mingles with an ovum of the chromosome (X), the formed zygote will be male (XY), whereas the embryo will be female (XX) if the sperm (X) mingles with an (X) ovum.  So, the sex of the embryo is determined by the sperm (the male), rather than the ovum (the female).

After 5 hours of forming the zygote, which is the primary human cell containing 46 chromosomes, the dominant and recessive genetic characteristics can appear in the parent's sons or grandsons (the stage of genetic programming) .  The zygote is then divided quickly (Fig. 3) without a change in size and move from the Fallopian Tube (connecting the ovary and the uterus) towards the uterus, where it is implanted as seeds are implanted in the soil. 

3-     The secretion of Progesterone (pregnancy hormone) helps stabilize the uterus and slows down the uterine contractions.

The process of fertilization and the travel of the zygote to the uterus continue for about 6 days, and the zygote keeps implanting ( known as blastocyst) and growing in the uterus wall for 15 days, when the Alaqa (thick clotted blood) stage begins.

“Nutfa” in Arabic means “very little water” or “a drop of water”. This coincides with man’s water which contain sperms as part of its components.  The sperm or (spermatozoon) is reproduced from the despised lowly water (nutfa) and looks like a long-tailed fish (this is one of the meanings of Sulalah).  Allah the Almighty says;

The other meaning of  Sulalah is "extract", means the essential or best part of something . By either implication, it means "part of a whole" indicating that the origin of creation is from only part of man's fluid and not all of it (which contains many components as shown above) .  

Clarifying the role of the nutfa in creation, He the Almighty says;

“He has created man from a sperm (fluid-drop) and behold this same (man) becomes an open disputer.” (16: 4). 

The Quran tells us also that the essence of man is not the whole semen, but only a small part of it. this is explained in the Quran :

( أَيَحْسَبُ الْإِنسَانُ أَن يُتْرَكَ سُدًى ، أَلَمْ يَكُ نُطْفَةً مِّن مَّنِيٍّ يُمْنَى ) القيامة 36-37

As we have seen , the Quran informs us that man is made not from the entire semen, but only a small part of it. That the particular emphasis in this statement announces a fact only discovered by modern science is evidence that the statement is divine in origin. The divine statement also reiterates that man’s characteristics are determined and decreed in the nutfa stage, as He says

“Woe to man! What has made him reject (Allah)? From what stuff has He created him? From a nutfa (fluid-drop) He has created him, and then moulds him in due proportions.” (80: 17-19). 

And Allah says :

“Verily We created man of a fluid-drop (nutfa), mingling (amshaj) , in order to try him: so We gave him (the gifts of) hearing and sight.” (76:2).
The mingled nutfa in this verse reveals the Quran miraculous nature.  Nutfa, in Arabic, is a single small drop of water, but it was described here as (amshaj) , which means its structure consists of combined mixtures .  This fits with the scientific finding, as the zygote is shaped as a drop, and is simultaneously a mixture of male fluid chromosomes and female ovum chromosomes. 
 

“That He created the pairs, male and female, from a fluid-drop sperm as it is emitted.” (53: 45-46), confirming that man’s gender as male or female is determined when the sperm drop is emitted.  Who told the Prophet Mohammed that the sperm (nutfa) with one of its types (Y) or (X) is responsible for determining the sex of the embryo?  This was not discovered except after the invention of microscopes in the past century, when it was possible then to know that the embryo being  a male or female is only determined by the sperm (nutfa), rather than the ovum.  In other words, we were in the beginning of the 20^th century and the whole of mankind were not aware that the nutfa decrees if the embryo is male or female.  While the Quran, which was revealed  14 centuries ago, has stated this fact in a very clear manner. 

Here is a remarkable note!  We have mentioned earlier that the sperms are formed in the testicles, which in turn are created, as proved by embryology, from cells underneath the kidneys at the back and then go down to the lower abdomen at the last weeks of pregnancy. This is in confirmation of Allah’s saying :

“And remember when your Lord brought forth from the children of Adam, from their loins, their seeds…” (7: 172). 
This is a clear indication that the origin of progeny is at the region of the back where the embryonic testicles are formed.  So, praise be to Allah the Omniscient.