Define Semen 

Semen is also called seminal fluid. Semen definition - it is the organic fluid ejaculated from the male reproductive tract which contains sperm cells. It also contains liquid to form a seminal plasma which helps to keep sperm viable. To define semen, it is clear that semen is made from the combination of different fluids having amino acids, citrate, enzymes, fructose, galactose, acid phosphate, mucus and spermatozoa. In mature male, spermatozoa are produced by testes that contribute only ten percent of the total semen.

After going through semen definition, let us have a look at the diagram, components, and storage of semen. 

Image caption: Semen Diagram having floating spermatozoa.

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Components of Semen 

During ejaculation, the sperm passes through the ejaculatory duct and mixes with different fluid secreted by seminal vesicles, the prostate gland, bulbourethral glands to form semen. Seminal vesicle secretes the yellow colour fluid which is viscous in nature and rich in fructose. Seminal vesicles make up to 70% of the total semen. The secretion of the prostatic gland is a whitish thin fluid containing proteolytic enzymes, citric acid, phosphatase, and lipids. The bulbourethral gland secretes the fluid which helps in the lubrication of lumen in the urethra. 

Semen fluid containing seminal plasma provides protection and nutrition to the spermatozoa during their journey to the reproductive duct tract. The environment of the vagina is generally hostile in nature for spermatozoa, as it is very acidic, viscous and patrolled by immune cells. The components of the seminal plasma will reduce the hostile nature of the vagina. Smell and flavour of the semen are due to the basic amines like putrescine, spermine, spermidine, and cadaverine.

Healthy Semen 

Generally, healthy semen is a cloudy white or grey fluid having jelly-like consistency. But sometimes it is yellow in colour and smells (bleach) due to the presence of alkaline substances. These substances are important to fight against the acidic nature of the female genital tract. Healthy male semen consists of approximately 200 -500 million sperm are released in each ejaculation.

Semen Volume 

The amount of semen ejaculated per ejaculation is known as semen volume. According to the international society for sexual medicine, the average semen volume ejaculated ranges from 1.25 to 5 millilitre. In simple words, the amount is equal from one quarter to one teaspoon of semen. Always keep in mind that the volume of semen varies from one time to another time.


Highly fertile semen can be stored for seven days. Semen can be stored in diluent for example (IVT) Illini Variable Temperature diluent which is composed of sugar, salts, antibacterial agents, and gassed with carbon dioxide. There are also techniques for longer storage duration like semen cryopreservation. Longest semen preservation till date reported is for 21 years.

Did you know?

How is semen produced? Semen is not produced by the single gland. Semen consists of a combination of different components like sperm and different fluids secreted by glands like seminal vesicles, the prostate gland and the bulbourethral glands.

When a person is about to ejaculate, semen travels through the tube called vas deferens. While travelling, it picks some sugary substance that acts as rocket fuel. Other fluids are also added to it while travelling to the urethra. The finished product will have only 10% of sperm and rest consists of enzymes, Vitamin C, Calcium, Protein, Sodium, Zinc, Citric acid, and fructose sugar.

FAQs (Frequently Asked Questions)

1. How Sperms are Produced?

Answer. Sperms are produced in the testis, it nearly takes 10 weeks for single sperm to reach maturity. A healthy adult human male can produce around 70 to 150 million sperm per day. Once sperm is matured it is stored in the epididymis. It is a coil-like structure which runs across the top of each testicle. Sperm can stay for about two weeks before it is ejaculated or broken down or reabsorbed by the body.

2. How Does Sperm Fertilize an Egg?

Answer. After ejaculation, sperm goes on finding the egg. Primarily, sperm has to survive the acidic nature of women’s vagina and swim through the cervical mucus. Then they have to travel for about seven inches in the fallopian tube. Healthy sperm can reach the egg in 45 minutes and some straggler sperm can take up to 12 hours to reach. Only a few of the sperm makes it possible to reach the egg. But only one sperm fertilizes the egg by penetrating through it and others get trapped or en route.