Strictly speaking, the presence of one sperm and one egg is sufficient for fertilization to take place. However, during the sperms' journey through the female reproductive system, the majority of sperms are lost or perish. Therefore the total number of sperm introduced into the vagina during intercourse plays an important role when evaluating male fertility. Nevertheless, a routine sperm analysis takes many more male factors into account than just the number of sperms present in the sample.

Ejaculate (semen) consists of two components:

• Sperm cells (spermatozoa), produced in the testis 
• Seminal fluid, a nutrient rich plasma that is produced by the prostate and seminal vessels. The fluid contains amongst other things fructose and citric acid.   

Normal sperm cells.

Seminal fluid does not only serve as a means of transportation to the outside, but it also causes an increase in the pH value in the vagina. Seminal fluid has a pH value of 7.2-7.8 and serves as a protective buffer for the sperm cells against the more acidic environment within the vagina. Sperm becomes immobile in a pH environment lower than 6.2. Ejaculate is primarily a viscous substance, but due to a protein acting enzyme from the prostate it becomes more fluid at room temperature after 20-30 minutes. The same thing happens in the vagina and in a more liquid form, the majority of the seminal fluid quickly separates from the sperm cells.

The sperms' journey to the egg in the fallopian tube is a fight for survival. Therefore in order for a fertilization of the egg to be able to occur, the composition of the ejaculate is crucial. Namely; 

• the quantity and pH value of the semen
• The number of sperms per ml and in total 
• The quality of the sperm; shape, motility and vitality . 

•  a minimum of 1,5ml,
•  with at least 15 million sperms per ml, or a minimum total of 39 million,
• 58% thereof must be live, motile sperm,
•  with at least 4% having a normal form.
• The pH is also of great importance.