Sperm

Main article: Pregnancy and childbirth

Building

Sperm in section. The head contains all genetic material

{{# https://www.tadviser.ru/images/1/10/IMG 4248.MP4|100%|auto||Spermatozoa under microscope}}

Conception

Scientific discovery: Sperm and egg join like a key and lock

On October 17, 2024, Austrian specialists from the Research Institute of Molecular Pathology in Vienna reported that they were able to identify a key mechanism that allows the sperm to enter the egg. It is said that a special lock-key scheme is crucial to the fertilization process.

Fertilization begins when sperm stimulated by chemical signals are directed toward the egg. Upon reaching the target, they bind to the egg surface, initiating fusion of genetic material to form a zygote. However, the exact molecular mechanisms enabling this important interaction remained unclear. In the new work, the researchers used an artificial intelligence-powered AlphaFold program developed by Google's DeepMind division. This made it possible to shed light on the fundamental aspects of the fertilization process characteristic of all vertebrates.

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Scientists found that two previously known fertility-related proteins on the surface of sperm -- Izumo1 and Spaca6 -- interact not only with each other but also with a third, previously unknown protein that has been designated Tmem81. The complex of these three components acts as a kind of "key" that serves to unlock the "lock" on the surface of the egg.

Experiments in Danio fish and mice have shown that disruption of the system from Izumo1, Spaca6 and Tmem81 provokes infertility in males of both species. The findings, as noted, open new avenues for the development of promising treatments for infertility in humans. It is also said that the three-component sperm complex is evolutionarily preserved in all vertebrates, while the egg proteins interacting with it have changed in different species.^[1]

How Sperm Understand Where to Move Them

Main article: Reotaxis

How a sperm enters an egg

For successful conception, at least 10 million sperm must enter the uterus. Almost all of them meet with an egg, but only one penetrates inside. The fact is that after meeting an egg, sperm still need to overcome certain barriers.

Directly, to merge with the egg, the sperm must pass two shells: a radiant crown and a shiny shell. To overcome the radiant crown - the layer of cells surrounding the egg cell, the sperm uses a special enzyme located on the surface of the head and splitting structures connecting the cells of the radiant crown.

One sperm is incapable of destroying the radiant crown, requiring exposure to 300 sperm to loosen and disperse the cells of the radiant crown. The sperm that first reaches the shiny membrane is most likely to undergo fertilization. If it turns out to be defective, then fertilization will not take place.

Thus, 10 million male germ cells get to the egg, but only one penetrates inside - the most lucky.

In the video below, a prototype of a 2019 device that can deliver sperm (with movement defects) to the egg.

Such works bring us closer to solving the problem of infertility.

The sperm determines the sex of the child

The baby's sex is determined as soon as the egg is fertilized. In humans, the sex is determined by sperm, not the egg.

All normal human eggs contain an X chromosome. Spermatozoa may contain either the X- or Y-chromosome.

If the sperm contains a Y chromosome, then the infant will be male, and if X - then female.

2024: Ultrasound technology developed to boost sperm motility by 266% for IVF

On February 16, 2024, Australian scientists from Monash University announced the development of ultrasonic technology that allows several times to increase the mobility of flaccid sperm. This is said to open new avenues for fertility treatment in a non-invasive way.

During the study, experts concluded individual sperm in microdroplets and exposed them to ultrasound with a power of 800 mW and a frequency of 40 MHz. It turned out that 20 seconds of such "therapy" is enough to increase the sperm motility by 266%. At the same time, the proportion of inactive germ cells decreased from 36% to 10%.

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Sperm motility is one of the main factors affecting the likelihood of successful fertilization. The application of the new technology could potentially reduce the need for expensive and invasive procedures such as intracytoplasmic sperm injection (ICSI): it is an assisted reproductive technology that is applied when sperm are unable to fertilize an egg on their own. In ICSI cases, they are administered artificially using microsurgical instruments. This method is in addition to the in vitro fertilization (IVF) procedure.

Ultrasound leads to a significant improvement in sperm motility. This technology will be useful for men with severe oligospermia and poor sperm motility, and will also help embryologists choose sperm for injection into eggs when performing IVF, says Dr. Frank Quinn.

The new method, studies show, pauses any mitochondrial dysfunction that could lead to impaired mobility in male germ cells. It is noted that ultrasound technology has great potential to increase the success rates of fertilization even in the most difficult cases.^[2]

2023

Smartphones reduce sperm quality - a 10-year study proved

In October 2023, scientists from the University of Geneva found that frequent use of a smartphone reduces the quality of sperm in men. The results of the long-term study are published in the journal Fertility and Sterility. Read more here.

Sperm cells break Newton's third law

On October 11, 2023, Japanese scientists from Kyoto University released the results of a study suggesting that human sperm cells violate Newton's third law. The results of the work in the future can lead to the creation of tiny robots of the next generation with unique functions.

The named law states that for each action there is equal opposition to it. That is, the bodies act on each other with forces equal in modulus and opposite in direction. This principle is true for classical physics of movement, but when it comes to the microscopic world, Japanese experts say, everything is not so clear.

Human sperm breaks Newton's third law

Sperm move at the expense of the flagellum at the back, using it like a tail. The thick liquid environment surrounding these cells should theoretically quickly deplete all their powers, and therefore deprive sperm of the ability to move around. However, this does not happen in reality. Moreover, the speed of movement of a human sperm can reach 0.1 mm per second or more than 30 cm per hour. Scientists have found that these cells have a non-reciprocal effect on the environment, that is, they do not cause an equal reverse action. And this is a violation of Newton's third law.

Japanese researchers called this effect "strange elasticity." This property allows sperm to slide easily even in the thickest fluid without losing a lot of energy. And because many microorganisms have flagella, scientists suggest that there are many other tiny violators of the described law. Understanding the mechanism of flagella movement can help in the creation of microscopic robots capable of effectively moving in difficult conditions. Such robots will be able to find application in medicine and other areas.^[3]

How much does donor sperm cost in Russia

In the St. Petersburg Center for Family Planning, donor sperm of a foreign citizen is estimated at twice the price of a Russian - 16 thousand against 35 thousand rubles. This became known in mid-August 2023.

The correspondent of the newspaper "Argumenty i Fakty" talked with an employee of the clinic and he explained that the difference in price is associated with transportation from abroad in special containers of imported sperm - its delivery to St. Petersburg is not cheap.

Donor sperm of a foreign citizen is estimated at twice the price of a Russian

At the same time, semen is not included in the cost of artificial insemination or IVF services, its patients are paid separately. You can choose a biomaterial donor yourself - for this, the institution has catalogs.

The clinic found it difficult to answer the question of who is chosen more often by the fathers of their future children as a resident of St. Petersburg. According to the interlocutor of the publication, such statistics are not kept in the planning center.

According to the Russian Association for Human Reproduction (RARCHA), there are more than 7 thousand cases of donor sperm in Russia every year. At the same time, according to Olga Ulankina, obstetrician-gynecologist of the Gemotest laboratory, it is not easy to become such a donor: the applicant must meet certain requirements and successfully pass the selection.

She noted that in order to collect one suitable portion of sperm, the donor will need to donate his biomaterial 1-2 times a week within 5-10 weeks. Thus, taking into account the average cost of one delivery of 5 thousand rubles in just 3 months, a successful donor can earn up to 100 thousand rubles.

Clinics that take biomaterial and engage in assisted reproductive technologies can set additional rules. For example, regarding the presence of higher education and their own healthy children or the absence of allergies and tattoos, - said Olga Ulankina.[4]

Physical labour boosts male sperm count by 50%

In late February 2023, scientists at Harvard University and MIT published a study that found men with physically demanding jobs had nearly 50% higher sperm counts than their colleagues working in the office.

For the study, Minges-Alarcon and her team at Brigham and Women's Hospital analyzed 950 sperm samples from 377 men who sought fertility treatment between 2005 and 2019. The findings, in collaboration with the Harvard T.H. Chiang School of Public Health, were published in the journal Human Reproduction.

Men with physically challenging jobs have 1.5 times more sperm count than men with office jobs

Participants in the study, who had a median age of 36, had to self-report levels of exercise at work and how often they picked up heavy items during work. Samples were collected at Massachusetts General Hospital's Fertility Center, with many respondents appearing to have had sedentary work: 51% of men had a college degree and 76% described their physical activity at work as mild. In contrast, only 12% of participants reported having a high-physical job and 9% said they were working evening or shift shifts. However, the latter group had significantly higher spermogram scores overall. In men who claimed to spend most of the day lifting or moving heavy objects, sperm concentrations were 46% higher. Meanwhile, according to scientists, those who worked in evening or shift shifts had 24% higher testosterone than men who worked only during the day.

According to experts, exercise is associated with numerous health benefits for people, but few studies have looked at how work factors can affect health. Results from the MIT study suggest that physical activity during work may also be associated with significant improvements in male reproductive potential.^[5]

2022

Over the past 50 years, the quality of sperm of men in the world has deteriorated sharply

In mid-November 2022, researchers at the Icahn School of Medicine at Mount Sinai Medical Center and Hebrew University unveiled a study that says sperm counts have dropped by more than 50% in men around the world over the past 50 years. This reduced male fertility levels by half.

A study on 153 estimates of men who were likely unaware of their fertility shows that the average sperm concentration fell from about 101.2 million per ml to 49.0 million per ml between 1973 and 2018, a 51.6% drop. Total sperm counts dropped 62.3% over the same period. A study by the same team, reported in 2017, found sperm concentrations had more than halved in the past 40 years. However, at the time, due to a lack of data on other parts of the world, the findings focused on a region spanning Europe, North America and Australia. The latest study includes more recent data from 53 countries.

The quality of sperm of men in the world has deteriorated sharply

I think it's another signal that there's something wrong with the globe and that we need to do something about it. So yes, I think this is a crisis that we better overcome now until it reaches a critical point that could be irreversible... Such a decrease clearly indicates a decrease in the ability of the population to reproduce. This problem is not just for couples trying to have children. It is also a huge frost for society in the next 50 years, as fewer and fewer young people will work and support the growing number of elderly people, said Professor Hagai Levine, first author of the study from the Hebrew University of Jerusalem.

A decrease in sperm concentration was observed not only in the previously studied region, but also in Central and South America, Africa and Asia. What's more, the rate of decline appears to be increasing: Looking at data collected on every continent since 1972, the researchers found sperm concentrations decreased by 1.16% per year. However, when they only looked at data collected since 2000, the decline was 2.64% per year.

Previous studies have shown that fertility decreases if sperm concentrations drop below 40 million per ml. Although the latest estimate is above that threshold, Levine noted that this is the average figure, suggesting that the percentage of men with concentrations below that threshold has increased. The study took into account factors such as age and duration of absence of ejaculation, and excluded men suffering from infertility, it has its limitations, in particular, it did not consider other indicators of sperm quality.

While it is unclear what might be behind the apparent trend, one hypothesis is that endocrine-disrupting chemicals or other environmental factors affecting the fetus in the womb may play a role. Experts say factors such as smoking, alcohol, obesity and poor diet can also play a role, and that a healthy lifestyle can contribute to sperm counts. However, Levin dismissed similar concerns, adding that, in any case, the decline has been more pronounced in recent years.^[6]

Demand for sperm freezing has sharply increased in Russian clinics

In Russia, the demand for sperm freezing has grown sharply. According to the publication "Big City" in early October 2023 with reference to the capital's private clinics, people began to apply three times more often for the service of cryopreservation of reproductive biomaterial. Experts associate the situation with mobilization. Read more here.

2019: Sperm quality dropped by 50% in 80 years

In March 2019, the British University of Nottingham published the results of a study in which scientists talked about the impact of household goods on male infertility. Partly because of such products, sperm quality has declined by about 50% over 80 years.

The researchers examined the effects of dioctyl phthalate plasticizer (DEHP) and polychlorinated biphenyl 153 on sperm samples from donors and breeding dogs. DEHP is found in clothing, carpets, toys, wires and floor coverings, and biphenyl 153, which is a banned substance, is still found in the environment and food. Scientists used a small dose of substances that corresponds to the approximate amount of biphenyl and dioctyl phthalate that can be obtained by household contact with objects containing chemicals.

Popular household goods affect male health, scientists find out

It turned out that environmental pollutants found in homes and in the diet have the same adverse effect on the reproductive function of men and dogs and are fraught with infertility. Under the influence of chemicals in moderate quantities, fertility rates decreased. This was seen in decreased sperm motility and increased DNA fragmentation.

The data obtained as a result of the study, according to scientists, prove the role of household chemicals in reducing the birth rate and will be used to develop means of limiting the negative effects of such compounds on the human body.

Fertility centers in New Jersey and Spain conducted a joint study of 120 thousand cases of male infertility. The proportion of patients with a total of more than 15 million mobile sperm decreased from 85% in 2002-2005 to 79% in 2014-2017. The proportion of men with 0 to 5 million mobile sperm increased from 9% to 11.5% during this time^[7]

2016: Introduced sperm analyzer using a smartphone

In December 2016, Medical Electronic Systems announced a device for the study of male seminal fluid at home. A device called Yo works in tandem with a smartphone. Read more here.

1929

Advertising, 1929.

See also

• Infertility

Notes