Contents
Outside of the human body, sperm do not live very long. On the other hand, when women enter the body during intercourse, they can survive in it for up to several days. This makes fertilization possible even longer after intercourse – when ovulation occurs after a few days, the live sperm in the woman’s reproductive tract has a chance of penetrating the egg.
Sperm – structure and functions
Sperm are male sex cells, also known as gametes. Measuring approximately 0,05 millimeters, the sperm consists of several separate parts:
- a tail made of protein fibers that helps it “flow” towards the egg,
- an insert, i.e. a body that contains mitochondria that drive sperm movement,
- the head containing the nucleus, which stores the precious load of the sperm – genetic information, as well as the acrosomal follicle, a tiny structure at the tip of the sperm, full of enzymes that help sperm penetrate into the egg.
Each sperm cell contains 23 chromosomes, which is half the number of chromosomes in a typical human cell – it is known as the “haploid” cell. The chronosome is a DNA molecule, the material that guides the growth and development of the entire human body. The egg contains the other half. Together, they make a fully realized cell with 46 chromosomes (known as a “diploid” cell), which then divides to become all the other cells in the body. The fact that half of our DNA comes from the sperm and the other half from the egg means that we inherit some traits from each of our parents.
One of the most important things that a sperm genetics – and only sperm genetics – determines – is the baby’s physical gender. If you’ve ever heard of the terms “XX” (for female) and “XY” (for male), they refer to the shape of the chromosomes that contain sex-determining genes. Like all chromosomes, you get one (always X) from the egg and the other (X or Y) from the sperm.
Some emerging research suggests that the percentage of sperm that carries the X chromosome versus the percentage of sperm that carries the Y chromosome (in other words, his chances of fathering a boy or girl) in a given man may be genetically determined – and this is not always 50/50
If you want to explain to your child what a sperm looks like, you can choose the Sperm educational toy available on Medonet Market. It also works well as a scientific aid in doctor’s offices.
Sperm – spermatogenesis
Spermatozoa are made in the testicles by a process called spermatogenesis. Every day, the testes produce about 50-100 million viable sperm. It takes approximately 74 days to complete the sperm anatomy.
This process begins in the vessels of the testicle called the seminal tubules, where the stem cells divide to form immature, short-tailed haploid sperm. The sperm then travel to the epididymis, the duct behind each testicle, where they develop their fully mature sperm anatomy.
The sperm are stored in the epididymis until they ejaculate. During ejaculation, sperm travels from the epididymis to the urethra in the penis through another tube called the vas. If the sperm does not ejaculate, it is eventually reabsorbed into the epididymis.
Spermatogenesis begins in adolescence and continues, usually uninterrupted, until death. However, with age, there will be changes in the health and quantity of sperm. This process is driven by the male sex hormone testosterone.
Now you can check the sperm concentration at home. At Medonet Market you can buy Home semen analysis – MAGNI-MAN cassette test.
Semen parameters – what are they?
Three characteristics of sperm determine fertility: the amount of sperm in a semen (sperm count), the ability of the sperm to move (sperm mobility), and how many of them have normal anatomy and structure (sperm morphology). These parameters can be examined during semen analysis.
Sperm count and concentration
Sperm count is the total number of sperm cells in a certain amount of semen, the fluid that carries sperm out of the penis. The sperm concentration refers to how densely “packed” the sperm are in the semen. For example, a sample might contain 3 milliliters of semen and a total sperm count of 45 million, this would be a concentration of 15 million sperm per ml.
Fifteen million sperm per milliliter of semen is considered normal sperm concentration, but scientists have noticed that concentrations below 40 million / ml can reduce the likelihood of pregnancy. Too little sperm in semen is known as oligospermia, lack of sperm is known as azoospermia.
Sperm mobility
Sperm motility refers to the ability of sperm to move or “swim” which is necessary to move through the female reproductive system and fertilize the egg.
Sperm morphology
Morphology denotes the anatomy, structure, and shape of sperm. Every male has abnormal sperm anatomy. In fact, a healthy male may only have 4–14% of the normal sperm structure. Poor sperm morphology, as evidenced by a very low percentage of sperm with normal anatomy, is known as teratozoospermia
The editorial board recommends: Better nutrition means better sperm quality
How do sperm fertilize the egg?
Fertilization is the “race to the top” of the female reproductive system – from the vagina to the fallopian tubes, where the sperm meet the egg and fertilization takes place. On average, between 80 and 300 million sperm are released when you ejaculate. However, most are eliminated along the way – any abnormal or otherwise defective sperm is exposed to many of the dangers of travel, along with a high percentage of healthy sperm. In fact, less than 1 in a million of the primary ejaculation will reach the egg at the time of fertilization.
The journey to the egg is complex, full of obstacles and sometimes hostile. The acidic environment of the vagina eliminates any sperm that remains in it for too long. When the sperm reaches the cervix, they must pass through the mucus network.
A lot of sperm can be lost in the uterine lateral canals where they can survive for days. When they reach the fallopian tubes, many of them become attached to their surface, only a few pass into the ovum. It is assumed that this long, arduous journey is a natural way to eliminate weak sperm, so only the healthiest and strongest sperm will survive.
When the sperm reaches the top of the female reproductive system, it goes through the last stages that allow it to fertilize the egg: the chemical changes on the sperm surface allow the acrosome to access the egg and dissolve its outer layer and tail.
Finally, once the sperm has reached the cytoplasm of the egg, it releases its nucleus to connect with the egg. Immediately the outer layer of the egg – known as the clear zone – changes to become impermeable to extra sperm.
Semen quality is assessed using three main parameters: mobility, morphology and genetic health. In addition to quality, the quantity (number or concentration) of sperm is important for fertility because so much of the sperm is lost as it travels through the female reproductive system.
What is sperm mobility?
Sperm mobility is the ability of sperm to move efficiently. This is important for fertility as sperm has to pass through a woman’s reproductive system to reach the egg and fertilize it. Poor sperm motility may cause male infertility. There are two types of sperm motility, relating to the way individual sperm swim.
Progressive mobility refers to sperm that swim mostly in a straight line or in large circles. Non-progressive mobility refers to sperm that do not follow straight lines or swim in very tight circles.
In order for sperm to pass through the cervical mucus to fertilize a woman’s egg, it must have a progressive mobility of at least 25 micrometers per second. Poor sperm motility or asthenozoospermia is diagnosed when less than 32 percent of the sperm are able to move efficiently.
The causes of low sperm motility vary and many cases remain unexplained. Damage to the testes that produce and store sperm can affect sperm quality.
The most common causes of testicular damage are:
- testicular infection
- testicles cancer,
- testicular surgery,
- undescended testicles,
- testicular trauma.
Long-term use of anabolic steroids can reduce sperm count and motility. Drugs such as cannabis and cocaine, as well as some herbal remedies, can also affect sperm quality. Varicose veins, the condition of enlarged veins in the scrotum, are also associated with low sperm motility.
See: Ten Sins Against Fertility
What affects sperm quality?
Sperm can be particularly susceptible to environmental factors such as exposure to excessive heat or toxic chemicals. To protect fertility:
- do not smoke – men who smoke cigarettes are more likely to have a low sperm count. If you smoke, ask your doctor to help you stop smoking.
- limit alcohol – heavy alcohol consumption can lead to decreased testosterone production, impotence and decreased sperm production. If you choose to drink alcohol, do so in moderation
- avoid lubricants during sex – While more research is needed on the effects of lubricants on fertility, consider avoiding them during sex.
- talk to your doctor about the medications you are taking Calcium channel blockers, tricyclic antidepressants, antiandrogens, opioids and other medications can contribute to fertility problems. Anabolic steroids and other illegal drugs can have the same effect.
- watch out for toxins – exposure to pesticides, lead and other toxins can affect the quantity and quality of semen. If you have to work with toxins, do it safely. For example, wear protective clothing, use protective equipment such as goggles, and avoid skin contact with chemicals.
- elevated scrotal temperature can obstruct sperm production. While the benefits have not been fully proven, wearing loose underwear, restricting sitting, avoiding saunas and hot tubs, and limiting scrotal exposure to warm items like laptops can improve sperm quality.