Tag Archives: sperm

A new problem from air pollution: It could be affecting sperm quality

Air pollution doesn’t just kill millions prematurely every year, especially in developing countries, it also affects the human sex ratio at birth and cause birth defects. Now, a new study in China has found yet another problem, finding that chemicals or particles in the air may also target sperm quality — specifically sperm motility, the ability of sperm to move in the right direction.

Image credit: Wikipedia Commons.

Infertility is a big public health problem, affecting about 10% of all couples at reproductive age. Pure male factors, especially poor semen quality, account for 50% of all infertility cases, according to the World Health Organization. Evidence has also suggested recently a downward trend in semen quality, with a decline in sperm motility, and the causes are not entirely clear.

Genetic background plays a big part in poor semen quality, but the marked decline in sperm quality in recent years suggests there’s something else going on, and here’s where environmental factors enter. Studies have reported a link between particulate matter (PM) and semen quality, but so far, the connection has been rather inconsistent.

An international literature review published last year said there’s enough reason to believe that air pollution is affecting fertility in general. Fossil fuels have been found in people’s urine, semen, blood, and breast milk. Many of these pollutants are endocrine disruptors, altering the body’s hormonal systems.

In a new study, researchers from Tongji University in Shanghai explored the data records of almost 34,000 men, aged 34 on average, from 340 Chinese cities, all exposed to a varying degree of air pollution. Their wives got pregnant by using reproductive technology with their sperm between January 2013 and December 2019.

Pollution and sperm

With the data collected, the researchers looked for patterns in semen quality in relation to whether the participants had been exposed to amounts of PM smaller in diameter than 2.5 micrometers, between 2.5 and 10 micrometers and over 10 micrometers. This was done several moments before the patient’s visit to the hospital.

The researchers focused on sperm count, concentration and sperm motility. While they couldn’t find a direct link between air pollution and the first two factors, they did find that the more a patient was exposed to small PM, the lower the sperm total and progressive motility was. Progressive motility is the ability to swim forward and total motility is the ability to swim in general.

Specifically, there was an estimated 3.6% drop of sperm motility when exposed to PM smaller than 2.5 micrometers and a 2.4% decline when exposed to PM of 10 micrometers, the study showed. This means that different sizes of PM could have different effects on semen quality. The smaller the PM, the more likely it is to travel to the human lungs and potentially affect sperm quality.

The study showed that the effects of air pollution on sperm quality are more significant when the exposure occurs in the first part of the 90 days of sperm creation, known as spermatogenesis, instead of the other two phases. This could indicate that PM affects sperm on a genetic level. However, it’s all speculation at this point and further research will be needed to confirm this hypothesis.

“Poor sperm motility has raised global concern as a major cause of male infertility. Our findings add evidence that PM exposure during sperm motility development may contribute to reduced sperm motility. Although the estimated decrease in sperm motility was relatively small, it still resulted in significantly increased odds of asthenozoospermia (the medical term for reduced sperm motility),” the researchers wrote.

The study was published in the journal JAMA.

Some sperm cells swim faster and even poison their competition to climb to the top

It takes just one sperm to fertilize a woman’s egg and for each sperm that reaches the egg, there are millions that don’t. You probably knew that already, but here’s the thing: not all sperm cells are equal. Some have mutations in their DNA sequence that allow them to swim straighter, rather than in circles, and faster on average than their competition. What’s more, sperm cells can even employ gruesome tactics, such as poisoning their neighbors in order to enhance their odds of fertilizing the egg.

It’s not just about luck

 T-sperm outcompete their normal peers (+) in the race for the egg cell with genetic tricks, letting them swim in circles. Credit:  MPI f. Molecular Genetics/ Alexandra Amaral.

The difference between a ‘loser’ and a ‘winner’ sperm cell could be down to a protein: RAC1. In a new study, researchers at the Max Planck Institute for Molecular Genetics (MPIMG) in Germany studied mouse sperm cells under the microscope, finding that this protein is responsible for guiding the sperm in the right direction by chemically signaling from the outside and activating other proteins.

The RAC1 protein plays a critical role in controlling the motility of sperm, in particular the average path velocity and linearity. This protein is produced in sperm that carry a particular DNA sequence known as the t-haplotype.

The researchers in Germany knew from previous research that it is thanks to this genetic sequence that some sperm swim in a straighter path and at a faster velocity than sperm lacking the t-haplotype. However, they were shocked to learn that t-haplotype sperm can also ‘poison’ their competition by injecting them with certain genes that inhibit movement.

“Sperm with the t-haplotype manage to disable sperm without it,” study co-author Bernhard Herrmann, director at the MPIMG, said in a statement. “The trick is that the t‑haplotype ‘poisons’ all sperm, but at the same time produces an antidote, which acts only in t-sperm [those with the t-haplotype] and protects them.”

In other words, it literally is a race for life (or death) for the millions of sperm cells on a quest to fertilize egg cells — and luck seems to play a minor role.

“Imagine a marathon, in which all participants get poisoned drinking water, but some runners also take an antidote,” said Herrmann, who is also the director of the Institute of Medical Genetics at Charité – Universitätsmedizin Berlin. That’s the same hospital where Kremlin critic and Russian opposition leader Alexei Navalny was treated after being poisoned, allegedly by the Russian government.

According to experiments, the vast majority of sperm cells that made little progress on their paths were genetically “normal”, whereas those that moved in a straight and optimal path mostly had the t-haplotype genetic factor. Poisoned cells literally swam in circles until they died. Meanwhile,  t-haplotype sperm that had the antidote that inhibited the effects of the “poison” charge straight ahead.

“Our data highlight the fact that sperm cells are ruthless competitors,” says Herrmann. “Genetic differences can give individual sperm an advantage in the race for life, thus promoting the transmission of particular gene variants to the next generation,” says the scientist.

The findings were reported in the journal PLOS Genetics.

How the sperm’s waggy tail enables the miracle of life

Credit: Pixabay.

Out of the millions of sperm that embark on the perilous journey to fertilize the egg, only a dozen or so cells are able to fully penetrate the reproductive tract, crossing the cervical mucus. Out of all of them, a single cell is allowed to fertilize the egg — winner takes all. A new study reveals how these motile cells are able to swim through so many obstacles, showing that the tails of human sperm have a reinforced outer-layer that allows it to break through the cervical mucus barrier which can be 100 times more viscous than water.

And the winner is…

Researchers at the University of York performed a computer model of different sperm tails — or flagella — from two types of animals: those that fertilize inside the body, such as humans and other mammals, and those that fertilize outside the body by releasing sperm into the environment like the sea urchin. The model showed that the tails of human and sea urchin sperm share many characteristics with one important distinction — the sperm in mammals have a reinforcing outer layer that offers extra strength and stability.

When the researchers released a virtual sea urchin-like sperm to swim through a liquid that mimicked the viscosity of the cervical mucus, they found that the tails quickly buckled under the pressure. Meanwhile, human sperm convulsed violently in a low-viscosity liquid like water but swam in a powerful rhythmic wave in a thicker fluid.

“We still don’t fully understand how, but a sperm’s ability to swim could be associated with genetic integrity. Cervical mucus forms part of the process in the female body of ensuring only the best swimmers make it to the egg,” Dr. Hermes Gadêlha, from the Department of Mathematics at the University of York, said in a statement.

The researchers think that the sperm’s flagella adapted to swim through thicker fluids, although it is not clear which evolved first — the stronger sperm or the cervical mucus, or whether they co-evolved. The findings could lead to better screening methods such that only the sturdiest sperm is selected for in vitro fertilization (IVF) treatments.

“During the sperm selection process, IVF clinics don’t currently use a highly viscous liquid to test for the best sperm as until now it was not entirely clear whether this is important. Our study suggests that more clinical tests and research are needed to explore the impact of this element of the natural environment when selecting sperm for IVF treatments.”

There are still many mysteries surrounding sperm. For instance, scientists still don’t know how sperm is able to control its movement and make decisions, but future research might shed light on this.

“We know that, just like in our arms and legs, sperm have tiny muscles which allow their tails to bend— but nobody knows how this is orchestrated inside the tail, at the nanometric scale,” said Dr. Gadêlha.

“Sperm are an architype of self-organisation—movement seems to be happening automatically, perhaps because of a complex combination of many mechanisms at play.”

The findings appeared in the Journal of the Royal Society Interface.

Men wearing tight underwear have lower sperm count

Men who wear boxers have a significantly higher sperm count and sperm concentration compared to those that sport tighter underwear. The findings, however, do not suggest that tight underwear actually have any effect on fertility.

Credit: Flickr.

The study led by Lidia Mínguez-­Alarcón, a research scientist at Harvard T.H. Chan School of Public Health, is the most comprehensive of its kind. The research team recruited 656 male partners of couples who were seeking infertility treatment at the Massachusetts General Hospital between 2000 and 2017. The male participants were aged 18 to 56, and had an average body mass index (BMI) of 26.

Among the 656 male participants, 53% reported wearing boxer shorts. This group tended to be younger, slimmer, and more likely to take hot baths than men who wore more tightly fitting underwear. Each male provided a semen sample and blood sample and answered a questionnaire about the style of underwear they most frequently used in the preceding three months.

According to the results, the boxer short group displayed 25% higher sperm concentration and 17% higher sperm count than the tight underwear group. Researchers adjusted for factors that might affect the results, such as BMI, physical activity, hot baths, and smoking.

The men who wore tighter underwear also had higher levels of follicle stimulating hormone (FSH) in their blood (14% more than the boxer short group). This hormone is known to be produced by the brain to stimulate sperm production, signaling that the body is trying to compensate for a lower sperm count. There were no recorded differences between the two groups in terms of other reproductive hormones or damage to the sperm’s DNA.

There are, however, a number of limitations to this study, which readers should be aware of. Firstly, the findings are based on men visiting a fertility center, so it may not be possible to generalize the conclusions. It is also true that the men involved in the study had a good semen quality relative to the World Health Organization’s reference standards. Secondly, this is a correlative study; tight underwear being associated with lower sperm count doesn’t prove that the type of underwear used is responsible for the observed effect.

And at the end of the day, men nowadays have bigger problems to worry about than which style of underwear to buy. A 2017 study found that men living North America, Europe, Australia, and New Zealand have a 52.4% lower sperm concentration and a 59.3% lower sperm count than they had 50 years ago.

According to Hagai Levine, an epidemiologist and public health physician at the Hebrew University-Hadassah, we don’t yet know for sure what caused this steep drop in sperm in the Western world. We do know, however, that endocrine disruptor exposure in utero, such as stress or smoking while the mother is pregnant, can harm the male’s fertility potential. It’s far more likely, however, that exposure later in life to man-made chemicals like pesticides or the effects of obesity cause such a pronounced effect.

If you’re reading this and feel a bit concerned, bear in mind that it only takes one sperm to fertilize one egg. Even if your tight underwear may be lowering your sperm count, you still have plenty of able swimmers. That being said, men with fertility problems could try switching to looser underwear, as it is a cost-effective, low-risk lifestyle change that may improve semen quality (although this is not discussed in the present study).

The findings appeared in the journal Human Reproduction.

Sperm plants.

NASA is sending sperm to the ISS — here’s why

The last resupply shuttle sent to the ISS brought the crew over 5,000 pounds of supplies and a few samples of sperm, to boot.

Sperm plants.

Image credits Thomas Breher.

Ever dream of going to space, maybe even blast off to a new life on Mars? I sure do. What about finding that special someone to love, someone to settle down and start a family with? Well, I have some good news and some bad news: you can probably do either of the two — but currently, we don’t know if you can do both at the same time.

The birds, the bees and the Falcon 9

Put quite simply, we don’t know how to succeed at the deed in space. We don’t even know if we can actually reproduce in microgravity, if all the biological cogs function as intended outside the environmental conditions of Earth. Luckily, NASA has our back, and they’re starting from the basics: last week, the agency sent several sperm samples to the ISS, planning to observe how the cells behave in space. It may sound silly, but knowing whether or not we can make babies in space (and how to best go about it) could make the difference between a successful deep-space mission or a complete failure.

As part of the “Mission Micro-11“, astronauts aboard the ISS will receive and then test samples of human and bull semen (these will act as controls). What NASA wants to determine right now is if the sperm can move with enough freedom and speed to fuse with an egg inside the station’s Microgravity Science Glovebox — an instrument which NASA amusingly describes as “particularly suited for handling hazardous materials when the crew is present.”

Before you ask — yes; yes there are six full-grown men aboard the ISS right now, and one can’t help but observe they might have had a different method of obtaining such samples you know, handy. NASA, however, didn’t want to have them go above and beyond the call of duty, with LiveScience’ Rafi Letzter noting it’s “understandable why the space agency didn’t go that route, if for no other reason than the limits of what can be reasonably demanded in even an outer space workplace.”

[Read More] Nobody’s in a loving mood when faced with a lack of food — not even astronauts. So here’s what they used to eat, what they eat today, and a look at what they’ll eat on the treck to Mars.

Chuckling aside, the experiment should help us gain a better understanding of how these cells fare in space — especially since previous research has shown that the lack of gravity could interfere with the normal functioning of sperm. While the cells themselves might be able to function properly, we still don’t know if they can actually fuse with the egg in these conditions.

Still, don’t give up on astronaut school just yet — right now, we’re looking at how well reproductive cells would function aboard the ISS. Later research will have to determine everything else: can humans give birth in microgravity? Can we insulate newborns from space radiation, and if not, how will it affect their development? And, perhaps most excitingly, how exactly does one go about having sex in outer space?

I for one, am willing to dedicate my body to that bit of science.

Sperm

Scientists make healthy sperm in the lab, raising hope for those suffering from genetic male infertility

XYY syndrome is one of the most usual causes that renders some men unable to father children. About one in 500 boys are born with either an extra X or Y chromosome giving a total of 47 chromosomes instead of the usual 46. Often symptoms may be subtle and many people do not realize they are affected, but one common consequence is sterility.

This doesn’t necessarily mean that such men can’t pass on their genes to offspring, in this day and age. British researchers at the London’s Francis Crick Institute showed that it’s possible to create sperm in the lab starting from small pieces of connective tissue taken from the ears of infertile male mice.

Sperm

Credit: Max Pexels.

Back to the cellular roots

For cells to differentiate into tissue that would eventually become skin, neurons, or that clump to form the liver or heart, they first start from stem cells. Today, however, it’s possible to go through the reverse process — turning tissue cells into undifferentiated ones called induced pluripotent stem cells (iPS). This enables the development of an unlimited source of any type of human cell needed for therapeutic purposes.

This is truly a very powerful method and in the 10 years since Nobel Prize-winner Dr. Shinya Yamanaka discovered IPSCs, regenerative medicine and drug discovery-development have accelerated their use of these cells. IPS cells can be used, for instance, to grow new organs in the lab that are an exact biological fit for any donor.

Diseases such as Alzheimer’s, Parkinson’s, Huntington’s and Down’s syndrome now have models that forego the use of ethically controversial ECSs. For drug screening and development, IPSCs are in use for in-vitro studies since these cells are capable of immortal growth in culture and provide genuine, human testable models. New drugs can be screened against cell culture models to determine their safety and efficacy, thanks to IPSCs.

From ear tissue to sperm…

In our case, the researchers transformed fibroblast connective tissue cells collected from sterile male mice into stem cells. In the process, the extra chromosome disappeared. The stem cells were then coaxed to differentiate or develop into immature sperm cells.

When these cells were injected into the testis of mice, they became properly functioning and healthy sperm. And ultimately, it was this sperm that was used to fertilize eggs, leading to healthy offspring.

Theoretically, it should be possible to translate the findings to men that have three sex chromosomes. The researchers went a step further into proving this by showing that they could make stem cells from XYY men’s fibroblasts which lacked the extra chromosome.

“The findings have relevance to overcoming infertility and other trisomic phenotypes,” the authors wrote in their paper.

The only huge drawback that would prevent a clinical trial is safety. Some of the mice that were injected with the immature sperm developed tumors and right now there is no way to make viable sperm outside the body, though that may change.

In any event, these are very encouraging results. If the scientists can find a way to vastly reduce the risk of tumor or can develop a method that can render healthy sperm in a lab tube, many men would be grateful. Like most things in experimental medicine, however, it might take another decade before this happens.

The findings were reported in the journal Science.

sperm count

Western males have lost nearly 60% of their sperm count since the 1970s

A striking new study published in the journal Human Reproduction Update found a drastic drop in both sperm concentration and sperm count among men in the Western world. According to data from 185 studies spanning 1973 to 2011,  the researchers saw a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm counts. Though there’s isn’t any official explanation yet, scientists think this steep decline in sperm count might be caused by exposure to new man-made chemicals like certain pesticides.

sperm count

Men’s sperm is not as ‘bright’ as it used to be. Credit: Pixabay.

The study covered men living in North America, Europe, Australia, and New Zealand who saw a steep decline in sperm count and concentration that wasn’t reported elsewhere. However, this may be due to the fact that proper data is less readily available in non-Western countries so it may be that men in Southeast Asia or Africa, for instance, may see similar significant reductions in sperm quality. We just don’t have the data yet.

A man’s fertility generally relies on the quantity and quality of his sperm. If the number of sperm a man ejaculates is low or if the sperm is of a poor quality, it will be difficult, and sometimes impossible, for it to lead to a pregnancy. But though the new findings might sound disturbing — after all, we’re talking about men who now have half as much sperm as they did 50 years ago — significant effects on population growth will only be seen when a significant proportion of the population has very low fertility.

At the same time, given the significant public health risks, the findings warrant urgent research. Previously, studies found that sperm count is related to increased morbidity and mortality, besides the obvious problems relating to fertility. Already, the fraction of men whose sperm counts are below the threshold for subfertility or infertility is increasing.

Credit: Hebrew University.

Credit: Hebrew University.

According to lead researcher Hagai Levine, an epidemiologist and public health physician at the Hebrew University-Hadassah, we don’t yet know for sure what caused this steep drop in sperm. We do know, however, that endocrine disruptor exposure in utero, such as stress or smoking while the mother is pregnant, can harm the male’s fertility potential. It’s far more likely, however, that exposure later in life from man-made chemicals like pesticides or the effects of obesity cause such a pronounced effect.

“One possible explanation is that men residing in Western countries over the last decades were exposed to new man-made chemicals during their life course, and there is more and more evidence that these chemicals hurt their reproductive function. We also need local knowledge regarding exposure and effects. For example, I am studying pesticides exposure and male fertility in Israel, as pesticides exposure is common,” Levine told ResearchGate. 

Nobody knows if this trend will continue on its descending path. One could argue that at some point the existence of our whole species could be threatened if sperm count drops at its current rate. The truth is we don’t know much yet. We just know things are bad right now and more urgent research is required to get to the bottom of things before it might be too late.

Mouse space sperm could pave a new era of space exploration

How one of the big questions about a potential space age was answered.

These baby mice were born from sperm flown aboard the International Space Station for about nine months. Image credits: Teruhiko Wakayama.

If we want to discuss long-term space travel or some sort of colonization, there’s one thing which always comes up: reproduction. We’re good at that on Earth (perhaps even too good, I’d say), but can we do it in outer space or on Mars? This isn’t just some random question, we genuinely don’t have a good idea how reproduction is affected by low-gravity and increased radiation. Well, according to a study published this week in Proceedings of the National Academy of Sciences, we shouldn’t worry too much about that: researchers used freeze-dried sperm stored on the International Space Station (for nine months), and it produced healthy offspring. While this doesn’t necessarily mean the same applies to humans, it’s quite promising.

Kris Lehnhardt, a physician at George Washington University who specializes in emergency and extreme-environment medicine comments on how much we don’t know about these aspects:

“We really don’t know any of the things that we need to know to say that human reproduction in space is going to be successful or safe,” he says. “It’s not been studied in much detail.”

No one has really had sex in outer space (not officially, at least), so we don’t really know how that works. With all this in mind, developmental biologist Teruhiko Wakayama wanted to answer some of the questions regarding the safety of reproduction in outer space.

“We found that only a few studies were performed about mammalian reproduction in space, and most of them showed no clear results due to the difficulty of taking the mice or rat into space,” says Wakayama, of Japan’s University of Yamanashi.

So he kicked up project “Space Pup,” which had the official goal of studying the difficulties of mammalian reproduction in outer space — focusing on mice. After extracting sperm from mice, he handed it to astronauts who stored it on the ISS from August 2013 to May 2014, after which it was brought back to Earth, fertilized in vitro and used on female mice. The females produced healthy offspring, who in turn produced healthy offspring — showing no sign of health or genetic problems.
What’s really interesting is that this happened although the sperm itself did show some evidence of DNA damage. This indicates some intriguing resilience, but it’s also worrying: If we are to travel to Mars or beyond, there would be even more radiation, doing likely even more damage.

“The radiation exposures that are reported in the paper are nowhere near the level of the radiation exposures that are going to be experienced once we travel beyond the protection of the Van Allen belt,” Joe Tash of the University of Kansas Medical Center told National Geographic, referring to another layer of radiation shielding that’s wrapped around Earth and that envelops the ISS.

The findings aren’t necessarily surprising. Astronauts go on the ISS all the time, and they can still have babies. Even those who spend lengthy periods there and even go out for spacewalks and are exposed to extra radiation do quite fine. Still, sperm is one of the most vulnerable cells, and if something were to go wrong (such as too much exposure to radiation), that’s pretty much the first place you’d look for damage. However, this still doesn’t tell us anything about how microgravity and increased radiation affect conception (done the old fashioned way), pregnancy, fetal development, or even giving birth. Could we safely have space babies? That’s an open question.

Now, Wakayama wants to try the other thing: send some fertilized mouse eggs to the ISS and see how they fare, as well as try similar things with cryo-preserved human sperm (not fertilize someone, just take it to outer space, bring it back, and study it).

Journal Reference: Sayaka Wakayama et al — Healthy offspring from freeze-dried mouse spermatozoa held on the International Space Station for 9 months. doi: 10.1073/pnas.1701425114

human sperm

Experimental male birth control seems to work, but the side effects are pretty nasty

human sperm

Credit: YouTube

While there are numerous birth control options for women, men are largely limited to condoms. That or a vasectomy, and let’s be honest not a whole lot of men are interested in such an invasive procedure. For some years, scientists have been working on a version of ‘the pill’ for men. This drug, which has so far been administered as an injection, uses hormones to lower the sperm count. A new paper concludes that this method is effective at preventing pregnancies, however, experiments had to be stopped early because of the side effects like depression and other mood disorders.

In other words, these birth control shots were not safe. So, yeah, I think men will stick to condoms for a long time.

However, these were effective. The researchers at the World Health Organization (WHO) in Geneva who carried out the study say the shots were 97% effective, based on tests where 270 men enrolled. The monogamous men were aged 18-45 and their partners had to sign up as well.

It takes only one sperm cell to fertilize a woman’s egg, but during one jizz 200 million competitors are ejaculated. Moreover, sperm is produced constantly at a high rate, so to suppress it scientists need to inject large quantities of hormones.

For this particular experiment, two hormones were injected: progesterone and a form of testosterone. First, each participant’s sperm was counted to ensure everything was normal, then every eight weeks the men were given a shot full of the hormones. Each participant was monitored for up to six months until their sperm count dropped to a million since a man is considered fertile if he has at least 15 million sperm per milliliter of semen. Past this point, the participants were mandated to rely only on the jab and no other forms of contraception. Yes, this was one tough study to handle as a volunteer.

Once the study ended, the researchers monitored the participants’ sperm to assess their health. Besides some troubling side effects like acne and serious mood disorders, the researchers note that eight men didn’t recover their initial sperm count a year after the study ended.

To be fair, male birth control pills or injections have been researchers for two decades, and all have their drawbacks. This latest study published in the Journal of Clinical Endocrinology & Metabolism seems to be the most promising yet.

Other interesting research in this field includes a pill that blocks ejaculation and immune-suppressing drugs.

“This has been one step in a long journey of finding the right combination for male hormonal contraception,” Dr Mario Festin from WHO and lead author of the paper said.

Festin and colleagues are now planning to tweak the hormonal concentration. They also plan on using a different delivering medium like gels, since shots are too invasive.

It’s worth noting that 75 percent of the men who enrolled in the trial said they’d be willing to use this contraceptive measure again. Would you?

 

Dog fertility has gone down significantly, and we’re probably to blame

A new study has found that dog fertility has suffered a sharp decline in the past three decades, likely due to environmental or food contaminants.

American type Golden Retriever, photo by Golden dust / Wikipedia

Dogs are man’s best friend and for millennia, humanity has intertwined with their existence. We’ve changed how dogs feed, their behavior, we’ve created countless breeds based on our needs and desires – perhaps to the point where our actions could be considered inconsiderate or even reckless, but that’s beyond the point. This new study found that man-made contaminants are affecting dogs in a new, more subtle way: by damaging their sperm.

The study analyzed five dog breeds: labrador retriever, golden retriever, curly coat retriever, border collie and German shepherd. They collected semen from 42-97 dogs every year for the past 27 years, finding a significant decrease in quality.

Dr Richard Lea from the University of Nottingham led the study. He said:

“This is the first time that such a decline in male fertility has been reported in the dog and we believe this is due to environmental contaminants, some of which we have detected in dog food and in the sperm and testes of the animals themselves.”

This might not seem like such a big deal, but as ‘man’s best friend,’ dogs’ and humans’ fate seems tightly connected. Basically, we share the same environment as well as a number of physical characteristics, so whatever is affecting them may actually affect us. In fact, there is quite a stirred discussion regarding the quality of human sperm in recent years, with a number of medical experts claiming a decline.

“While further research is needed to conclusively demonstrate a link, the dog may indeed be a sentinel for humans – it shares the same environment, exhibits the same range of diseases, many with the same frequency and responds in a similar way to therapies.”

Regarding human sperm, we still don’t know for sure how “good” it is. There is a trove of scientific data indicating a decline in the past 70 years, but many have criticized the variability of data, due to the improvements in the available technology and laboratory personnel training.

The data in the dog study is more valuable in this sense, because it was gathered at the same lab, with the same technology and with similar techniques. It seems to support the idea of a decline in human sperm quality. Dr Lea added:

“The Nottingham study presents a unique set of reliable data from a controlled population which is free from these factors. This raises the tantalising prospect that the decline in canine semen quality has an environmental cause and begs the question whether a similar effect could also be observed in human male fertility.”

Journal Reference: Environmental Chemicals Impact Semen Quality in Dogs in Vitro and May be Associated with a Temporal Decline in Quality and Increased Cryptorchidis.

Male dogs are becoming less fertile, and researchers believe it’s happening to us next

Researchers have determined that the fertility of male dogs all over Britain has been steadily declining over the past three decades, for a whopping 30 percent across five common breeds. There isn’t any real danger of them losing their ability to reproduce anytime soon, but the findings could have serious implications for their human owners, the team believes.

My what does WHAT?!
Image credits Zach Zupancic/Flickr.

Ok, I don’t know about you but there’s two things that consistently make my day better no matter what’s going down: the dog jumping up and down for joy when he sees me come home, and the fact that my plumbing works like a charm. But, in a kind of depressing quantum link, the two of them seem to be connected — and science says there’ll be a whole lot less up and down going on.

“The dogs who share our homes are exposed to similar contaminants as we are, so the dog is a sentinel for human exposure,” said lead researcher Richard G. Lea, from the University of Nottingham in the UK, for the The New York Times.

Lea and his team have been assessing the fertility of a population of male service dogs at an English center for disabled people. They started in 1988, and since then they’ve analyzed a total of 232 dogs of five different breeds — Labrador retrievers, golden retrievers, curly coat retrievers, border collies and German shepherds. The team chose to work with these dogs because their health and lineage are excellently recorded and they’re all being raised in one location in the same conditions.

Each year, the team would test the fertility of a selection of 42 to 97 dogs via sperm samples. At varying intervals throughout the 26 years of study, the dogs with the poorest sperm quality were removed from the test group. When they measured the percentage of sperm with healthy motility — the ability to swim in a straight line — the researchers found that it dropped by 2.4% each year. Even when not taking data from the dogs who were removed into account, sperm motility declined by an average of 1.2% every year from 2002 to 2014, for an overall decline of 30% over the entire study’ duration.

And the bad news don’t end here.

“Between 1994 and 2014, they also noticed that the mortality rate of the female puppies, although small, showed a threefold increase,” writes Jan Hoffman for the NY Times. “And the incidence of undescended testicles in male puppies, also small, had a 10-fold increase, to 1 percent from 0.1.”

Lea’s team isn’t sure what’s causing this, but they believe that it all comes down to the presence of environmental chemicals called PCBs and phthalates in the dog’s semen and testicles (removed by vets during routine desexing procedures.) Once widely used for paints and plastic masses, PCBs were banned back in the 1970s and ‘80s, and diethylhexyl phthalate (DEHP) has been noted for its potential health risks. But even if they’ve fallen out of use, their long half-life means that they’re virtually everywhere today. Including, as the team found, in trace amounts in the food the dogs eat.

“The scientists cannot determine how the chemicals were introduced into the food supply; these are not additives,” says Hoffman. “But Lea and his colleagues speculate that they could be in the packaging as well as in water that came into contact with any ingredients.”

Ok, so what do dogs’ little swimmers have to do with us? Well, the same chemicals that affect them affect us, too. There are more than 60 studies that report a recent decline in the quality of human semen in the years between 1938 and 1991. Their results are hotly debated, but the evidence that the incidence of undescended testicles in human babies and cases of testicular cancer are on the rise, isn’t. By itself, however, the data isn’t enough to establish a link between these chemicals and the effects the team is seeing — there are just too many other chemicals at play here.

“If you think about it, we are exposed to a cocktail. Who knows how many chemicals are out there and what they are doing?” Lea said.

“What we have been able to do here is just to pull out ones that we know are present, and we have tested those in terms of their effects and it does suggest there is an impact. The next stage – and it is a big next stage – is trying to tease out what else is there and how those chemicals are interacting.”

The paper, titled “Environmental chemicals impact dog semen quality in vitro and may be associated with a temporal decline in sperm motility and increased cryptorchidism” has been published online in Scientific Reports.

sunscreen

Half of sunscreens might disrupt sperm function

Women who use certain sunscreens might be at risk of infertility, as scientists found 45 percent of the tested products contained chemicals that mess with the function of sperm. It’s important to note that this research is still ongoing. Tests were made in vitro, using sperm cells in a solution that mimicked conditions inside the female fallopian tubes. Not even mice were tested yet, so take the findings with a grain of salt (i.e. don’t freak out just yet).

sunscreen

Image: Flickr

“These results are of concern and might explain in part why unexplained infertility is so prevalent,” said the study’s senior investigator, Niels Skakkebaek, MD, DMSc, a professor at the University of Copenhagen and a researcher at the Copenhagen University Hospital, Rigshospitalet.

Skakkebaek and colleagues studied  29 of the 31 UV filters allowed in sunscreens in the U.S. or the European Union (EU) on live sperm cells collected from healthy donors. The cells were placed in buffer solution.

The analysis was focused on calcium signaling, where changes in the concentrations of calcium ions causes the cell to behave differently. In sperm, this signaling is very important. CatSper is one of the most important calcium ion channels inside the human sperm cell. It’s the main receptor for progesterone, a hormone that attracts human sperm cells. When the hormone binds to the Catsper calcium channel, the interaction causes a temporary surge in calcium ions inside the sperm cell. This controls several sperm functions necessary for fertilization.

[MORE] What the SPF number on your sunscreen means

Researchers found 13 of 29 tested UV filters induced calcium ion influxes in the sperm cell.  “This effect began at very low doses of the chemicals, below the levels of some UV filters found in people after whole-body application of sunscreens,” Skakkebaek said. Nine of the thirteen filters specifically cause calcium ion influx in the CatSper channel, thereby mimicking the effect of progesterone.

“Our study suggests that regulatory agencies should have a closer look at the effects of UV filters on fertility before approval,” said Skakkebaek, who has since applied for funding to test these findings in an animal model.

UV filters are used in sunscreens that protect the body by absorbing UV rays, instead of reflecting them. Physical sunscreens that contain reflecting chemicals like zinc shouldn’t interfere with sperm function — if there’s anything that’s interfering in the first place. We’ll know more for certain after research on mice is carried out.

Some of the filters found to disrupt sperm function are: avobenzone, homosalate, meradimate, octisalate (also known as octyl salicylate), octinoxate (or octyl methoxycinnamate), octocrylene, oxybenzone (also called benzophenone-3 or BP-3) and padimate O.

via Science Alert

50 Million Year Old Sperm Found by Accident in Antarctica

Scientists have stumbled upon some incredibly old sperm in the wall of a fossilized cocoon in Antarctica. The remains of the long, thin cells represent the oldest animal sperm known to man – 50 million years old.

50-million-year-old spermatozoan entrapped on the inner surface of a cocoon wall from Antarctica (Photo: Department of Palaeobiology, Swedish Museum of Natural History)

Benjamin Bomfleur, a palaeobotanist at Stockholm’s Swedish Museum of Natural History and the lead author of the study describing this finding spotted the sperm cells as he was conducting an analysis on the inner surface of the cocoon fossil. He was using a very sensitive electron microscope and said that the discovery came as a total surprise, one that amused him thoroughly but that is also highly significant.

“A 50-million-year-old worm sperm from Antarctica?” he said between chuckles. “Who would have thought that’s possible?”

It makes sense that there are a lot of sperm inclusions in cocoon cells. The cocoons are secreted by some worms which then store sperm and eggs inside, so it seems reasonable to assume that sometimes, the sperm is stored incorrectly outside of the cocoon. But surviving for 50 million years… that’s truly remarkable! Before this, the oldest known animal sperm came from Baltic amber, 40 million years ago.

“The discovery was a big surprise, but the result of a detailed search and Steve’s (co-author Stephen McLoughlin) keen eye for the unusual. We both were aware that it may be rewarding to take a particularly close look at the cocoon fossils because they might contain “microinclusions” (like amber). It was then, Steve, who was analysing the structure of this particular cocoon fossil using a scanning electron microscope at very high magnification, first noticed the spermatozoa inclusions,” said Bomfleur.

For now, researchers don’t know exactly what worm left this sperm. Scanning electron microscope images show helical structures resembling drill-bits and beaded tails, which are highly characteristic of crayfish worms – closely related to earthworms and leeches that feed on material found on the surface of their crayfish hosts. However, scientists do have their hunches regarding what might have left this behind.

“At present detailed comparisons with living leeches are difficult. However, they do appear strikingly similar to those of ‘Branchiobdellida’ – a peculiar group of leech-like worms that is today only found living symbiotically on crayfish in the Northern Hemisphere. Quite perplexing!” Bomfleur told HT in an email interview.

Another fossilized spermatozoon fragment; the scale bar is 1 micrometre long. Dept Palaeobiol./Swedish Museum of Natural History

The structure of worm sperm cells has been studied in surprising detail in the past decades, but researchers only recently gained access to instruments that allowed them to thoroughly see the defining microstructures. Bomfleur thinks that future studies will reveal how the sperm of the worms changed as the species evolved.

“If it should turn out that we can get this information, all of a sudden we would basically unlock an entire fossil record for a group that hardly had any identifiable fossils before,” he says. Soft-bodied microorganisms that do not usually fossilize, including nematodes, have also been found preserved inside cocoons, but few researchers have studied them.

These cocoons may provide a unique window to the past, allowing an unprecedented view on worms – and yes, before you start wondering, worms are important. Jakob Vinther, who studies invertebrate evolution at the University of Bristol, UK, explains that understanding ancient worms could allow us to better understand the origin of earthworms and leeches.

“I think we might have a really interesting system here that can be sort of a hidden window to the past,” he says. “There could be a lot of potential hidden gems inside those cocoons.”

However, before your Jurassic Park dreams get amped, you should know that there’s absolutely no chance to get any DNA material from that sperm. Even if it is incredibly well preserved, it has no organic material.

“… even if they should be preserved with original ultrastructural details, the chemical make-up of the organic material will have changed from its original composition over time in the course of fossilisation––there will certainly be no extractable DNA left,” said Bomfleur.

Journal Reference: Benjamin Bomfleur, Thomas Mörs, Marco Ferraguti, Marcelo A. Reguero, Stephen McLoughlin. Fossilized spermatozoa preserved in a 50-Myr-old annelid cocoon from Antarctica. DOI: 10.1098/rsbl.2015.0431

 

Sparks Literally Fly When the Egg Meets Sperm, Spectacular Images Show

They say that when two people fall in love, you can see sparks flying. Well, that may or may not be true, but researchers from the US have shown that when sperm meets and egg – sparks definitely fly.

Fertilization Fireworks

A combined imaging approach was used to identify and characterise zinc-enriched packages in a mouse egg. Image courtesy from Northwestern University.

These are the first images captured at the exact moment when a mammal’s egg is fertilized, showing that in response, the egg releases billions of zinc atoms that create tiny ‘zinc sparks’ at the point of conception.

Northwestern University scientists had a hunch that this might be the case, so in order to prove their theory, they invented a a new fluorescent sensor that is able to track the movements of zinc in live cells. This allowed them to make a number of interesting findings, including an unprecedented view of an egg’s zinc-storage capabilities. The egg features some 8,000 zinc compartments, each one containing around one million zinc atoms; when it’s fertilized, it releases all those atoms in a firework-like display which lasts up to two hours.

The finding could lead to improved In Vitro Fertilization (IVF) results, showing which eggs have the highest quality.

“The amount of zinc released by an egg could be a great marker for identifying a high-quality fertilised egg, something we can’t do now,” said one of the team, ovarian biology expert, Teresa Woodruff, in the release. “If we can identify the best eggs, fewer embryos would need to be transferred during fertility treatments. Our findings will help move us toward this goal.”

Release of thousands of these packages results in the striking event called the zinc spark that is a hallmark of fertilization in mammals. In the images shown, bright fluorescent signal coming from the egg is a result of the release of groups of zinc-rich packages from the egg to form a zinc spark. Image courtesy of Northwesteern University.

The team used high-energy X-Ray visualizing techniques to see where the zinc atoms are at any given moment.

“On cue, at the time of fertilisation, we see the egg release thousands of packages, each dumping a million zinc atoms, and then it’s quiet. Then there is another burst of zinc release,” said co-author, Thomas O’Halloran, in the release. “Each egg has four or five of these periodic sparks. It is beautiful to see, orchestrated much like a symphony. We knew zinc was released by the egg in huge amounts, but we had no idea how the egg did this.”

Why Zinc?

Of course, this begs the question – why does the egg eliminate so much zinc? Well, zinc has a lot to do with the egg’s decision to grow into an embryo. This is a very complex process, but as fertilization occurs and the egg “decides” it will grow into an embryo, it eliminates the zinc.

“The egg first has to stockpile zinc and then must release some of the zinc to successfully navigate maturation, fertilization and the start of embryogenesis,” said O’Halloran. “But exactly how much zinc is involved in this remarkable process and where is it in the cell? We needed data to better understand the molecular mechanisms at work as an egg becomes a new organism.”

The study, which was published in the journal Nature Chemistry, provides the first quantitative physical measurements of zinc localization in single cells in a mammal. The researchers are now working to see if they can somehow correlate zinc sparks to egg quality, but this study also lays the basis for understanding how zinc fluxes can regulate events in multiple biological systems beyond the egg, including neurotransmission from zinc-enriched neurons in the brain and insulin-release in the pancreas.

Journal Reference: Emily L. Que, Reiner Bleher, Francesca E. Duncan, Betty Y. Kong, Sophie C. Gleber, Stefan Vogt, Si Chen, Seth A. Garwin, Amanda R. Bayer, Vinayak P. Dravid, Teresa K. Woodruff & Thomas V. O’Halloran. Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks. Nature Chemistrydoi:10.1038/nchem.2133

Sperm RNA carries marks of trauma

Scientists have shown that trauma can leave epigenetic marks – chemical changes that affect how DNA is expressed without altering its sequence. Basically, your traumatic experiences genetically affect your offspring.

tiripero/iStock/Thinkstock

Scientists have recently focused on the long term after effects of trauma, finding them to be numerous and diverse. The offspring of traumatized people are at a high risk of depression and anxiety, may have higher suicide rates – but this is difficult to explain genetically; one could argue that the traumatized parent is indirectly responsible for this, through his/her behavior, which is in turn influenced by the trauma. Now, researchers found that stress in early life alters the production of small RNAs, called microRNAs, in the sperm of mice. The mice show depressive behavior for a long time, and so do their offspring.

The study is notable for showing that sperm can be influenced by the father’s mental state, says Stephen Krawetz, a geneticist at Wayne State University School of Medicine in Detroit, Michigan, who studies microRNAs in human sperm and was not involved with this study.

“Dad is having a much larger role in the whole process, rather than just delivering his genome and being done with it,” he says. He adds that this is one of a growing number of studies to show that subtle changes in sperm microRNAs “set the stage for a huge plethora of other effects”.

Isabelle Mansuy, a neuroscientist at the University of Zurich, Switzerland, and her colleagues periodically separated mother mice from their young pups and exposed the mothers to stressful situations. They subjected the mice to this torturous experience every day, but at erratic times, so that the mothers couldn’t comfort their children in advance – morally, I find this disturbing, but from a strictly scientific point of view, you can’t argue with the method they used.

The males which were raised this way showed depressive behaviours and tended to underestimate risk, the study found. Their sperm also showed abnormally high expression of five microRNAs. One of these, miR-375, has been linked to stress and regulation of metabolism. When it came to the following generation, they were also more depressive than their control counterparts, even though they were never subjected to any trauma. To rule out the possibility that the effects of stress were transmitted socially, the researchers also collected RNA from the F1 males’ sperm and injected it into freshly fertilized eggs from untraumatized mice. This resulted in similar depressive behaviors which were passed onto the next generation.

While there is still much to be discovered about the biological underlying mechanisms, this is the first study to show that traumatized mammals affect their offspring directly through the sperm.

Source: Nature.

Armada of sperm headed for the egg. A birth control pill for men would stop ejaculation. Photo credit: blog.f1000.com

Male birth control pill may work by blocking sperm ejaculation

  • Male birth control pills have been researched for some time, however previous attempts have been found to be ineffective.
  • A new method that concentrates at blocking male sperm ejaculation, has been found to be effective in mice. A drug could be administered orally, just like the female version.
  • Before a male birth control pill can be released for humans, it will take a lot of time.

Armada of sperm headed for the egg. A birth control pill for men would stop ejaculation. Photo credit: blog.f1000.com

Armada of sperm headed for the egg. A birth control pill for men would stop ejaculation. Photo credit: blog.f1000.com

When ‘the pill’  appeared in the early 1960’s it  stirred a sexual revolution, while also offering a fantastic family planning tool. To this day, it is the most reliable contraception method and safe to use (almost), however as you might imagine it was a rather bumpy road at the beginning. Obviously, birth control pills are exclusively available to women, but why not a pill for men too? The challenges are numerous, and previous attempts showed numerous flaws and side effects. A new research by scientists at the Monash University in Australia took an alternate route at developing a possibly viable birth control pill for men by blocking sperm ejaculation, instead of sperm production. Findings show promising results in tests on mice, however we might be many years away from seeing such a product on the market.

The pill

Birth control pills work through several mechanisms, with their primary purpose being to stop ovulation. Since no egg is released, sperm fertilization is impossible and thus the woman can’t get pregnant. To do this, most pills release synthetic forms of estrogen and progestin. These exclusively female hormones stabilize a woman’s natural hormone levels indifferent of menstrual cycle. For the egg to be released by the ovaries, other hormones need to be signaled by an estrogen bump which typically occurs during mic-cycle. So simply by normalizing estrogen levels and avoiding a peak, the egg isn’t released and pregnancy is totally avoided.

Things a lot more complicated with men, and not just because estrogen doesn’t work on men – not in the way you’d want at least. For one, we’re not talking about stopping an egg from being released once a month. A birth control pill for men would need to stop each of the 1,500 sperm cells men produce each second. Hormonal treatments similar to the mechanics of the female version have proved to be clumsy, and produce numerous side effects. Attempts at halting the rapid production of sperm is similarly difficult, in part because a natural barrier between the blood and the testis, the site of sperm production, keeps drugs out.

Blocking ejaculation

A team of researchers led by  Sabatino Ventura of Monash University in Australia took an alternate route. Instead of concentrating on stopping sperm production, the scientists decided to look for a way to halt sperm ejaculation altogether. Sperm is produced inside the testicles and then stured in a coiled tube called the epididymis. During ejaculation, smooth muscles contract and propel the sperm out the epididymis, through a tube called the vas deferens, then into the urethra from which it is finally expelled. Muscle contraction is signaled by certain hormones which attach themselves to two receptors: α1A-adrenoceptors and P2X1-purinoceptors.

Previous attempts tried to block only the α1A-adrenoceptors, but tests on mice showed that  sperm still made its way to the urethra. Scientists suggest that the other receptor is compensating, leading to fertilization 50% of the time. For their study, Ventura and colleagues bred mice which were genetically modified to block both receptors. Both female and male mice were born lacking the two receptors and proceeded to mate as usual. It was found that female mice could still become pregnant following artificial insemination.

The modified males, however, didn’t fertilize the females. Closer inspection showed that the males’ vas deferens did not contract normally in response to stimulation, suggesting that the lack of receptors did stop sperm movement. What about side effects? Well, the two receptors are known to be linked to cardiovascular health, but males’ blood pressure only dropped by 10%.

Because the vas deferens is located  outside the blood-testicle barrier, this also means drugs that target these receptors could be administered orally – essentially,  a male birth control pill would thus be possible. More work will be required to test the side effects more thoroughly before clinical trials on human may begin – which will take many years no doubt.  In fact, drugs that block α1A-adrenoceptors are already on the market to treat benign prostate enlargement.

Even if a birth control pill for men would be release tomorrow with no side effects and completely reversible, there is still a big challenge in the way of its wide-scale usage. Of course, there is a psychological factor involved – men are very proud of their reproductive capabilities and being unable to ejaculate might not be the most appealing prospect for most.

“A lack of ejaculate has the potential to be disconcerting,” the researchers wrote in their study.

The findings were reported in a paper published in the journal Proceedings of the National Academy of Sciences.

Manipulative female squids consume sperm for nutrition

Benjamin Wegener, a researcher at Monash University’s School of Biological Sciences and his team has shown that for squids, it’s really a dog eat dog out there: certain females consume male ejaculate and sperm as if they were foods, providing more energy for both themselves and future eggs.

squids

For females, it’s really a big win – the sperm is very rich in nutrients, and while ejaculate ingestion has been documented in numerous other species, sperm consumptions is far less common.

“If males have their sperm consumed, rather than used for egg fertilization, they will lose that reproductive opportunity. Therefore, it is in the male’s best interests to try to ensure at least some of his sperm reaches the female’s eggs,” lead author Benjamin Wegener, a researcher at Monash University’s School of Biological Sciences, explained.

Other species which have been documented to consume ejaculate include carrion flies, picture wing flies, a strange marine invertebrate known as Spadella cephaloptera, a type of leech, a marine nudibranch and the southern bottletail squid (Sepiadarium austrinum); humans may ingest sperm, but it’s not part of the standard behavior during reproduction.

“This is an important distinction, as even if the female consumes some of the ejaculate in those internal fertilizers, at least some of the sperm remains inside in the reproductive tract,” he said. “For an external fertilizer with short-term sperm storage, if the female doesn’t lay eggs in time, the male loses his chance to fertilize the eggs.”

This raises many questions. Do the females actually sample the sperm and decide if they want to use it for reproduction or for nutrition? Do they trick unsuspecting, less desirable men into giving their semene? Those are questions yet to be answered.

“As the authors point out, she might even choose to eat the sperm packets from less attractive males and use the sperm from more attractive ones for fertilizing her eggs.”, added Tom Tregenza, a professor of evolutionary ecology at the University of Exeter.

Study

French sperm decreasing in quality

French people are among the healthiest nations in the world, but even so, their sperm is sinking, not swimming, according to a recent study.

The study analyzed the little swimmers from 26.600 men, taken in a span of 17 years, and they found a significant decrease in quality as time passes – both in concentration and morphology.

“To our knowledge, it is the first study concluding a severe and general decrease in sperm concentration and morphology at the scale of a whole country over a substantial period,” the authors wrote. “This constitutes a serious public health warning. The link with the environment particularly needs to be determined.”

Studies are scarce in this field – anecdotal report from sperm banks and small, local studies are pretty much the only source of information – which is actually kind of pretty sad, because despite the tabu nature of the subject, this is quite an important issue.

The researchers examined sperm samples from men who visited fertility clinics because of their female partners’ fertility problems – in other words, the guys had no problem whatsoever themselves. Over the 17 year period, a drop in concentration of 32.2 percent was found, averaging at 1.9 percent each year. If we were to put that in numbers, it translates to a drop from 73.6 million sperm per milliliter of semen in 1989 for an average 35-year-old man to 49.9 million sperm per milliliter in 2005. According to the WHO (World Health Organization), a fertile man has at least 15 million sperm per milliliter.

The next step is to figure out why this happens, and if it is limited to France or if it happens to the entire developed world, as a result of environmental factors.

Via LiveScience

Sperm captured in 3D for the first time, reveals corkscrewing swimming [with video]

Scientists have finally managed to track sperm patterns in 3D, for the first time in history. Bless their gifted brains, this remarkable achievement revealed some interesting and unexpected things: some sperm swim in corkscrew patterns, while others are hyperactive and hectic.

Aydogan Ozcan, the sperm study leader, placed sperm on a silicon sensor chip and used red and blue light to track their movement and plot their trajectories in 3D.

“The vast majority of the sperm followed a “typical” path-more or less a straight line. But some swam in a helical, or corkscrew, pattern previously only hinted at by fuzzy microscope results. Other sperm were labeled “hyperactive” due to their jerky direction changes, which sometimes sent them careening in reverse.”, he explained.

So it isn’t really a mad dash to the finish line for the little sperm, it’s actually a wiggly tap dance for some of them.

sperm donors

Sperm donors are manlier than non-donors

sperm donorsResearchers at Linköping University have taken up themselves to study the intricate personality of the sperm donor. What they found was that men who cared enough to preserve their heritage were more stable and mature than non-donors.

Rather extensive, as part of the study the researchers asked donors from all of Sweden’s seven sperm banks to fill in questionnaires relating to their temperament, character and demographic factors such as age, education and marital status –  the Temperament and Character Inventory personality scale or  TCI. The researchers then found non-donor subjects in the same demographics to match them up.

The study, which tried to paint a portrait of the common sperm donor in Sweden, concluded that there were significant differences on the temperament dimension of harm avoidance between the sperm donors and the comparison group, with lower means for sperm donors. Thus, the donors described themselves as being less worried, less uncertain and more energetic than men in the non-donating group.  Nearly half of the donors were in a relationship, and more than a third had their own children. It’s very likely that by now most of them have more kids than they can count.

Don’t think that these results apply for anyone who let one off in a plastic tube elsewhere in the world. For one, in Sweden sperm donors aren’t paid, so you don’t have your usual donors looking to make a quick buck to score some booze. They get something like covered travel and work expenses, but nothing more. So, one might easily add altruism to the number of already enchanting traits.

The sperm donors also showed significantly higher means on cooperativeness. This means that they described themselves as being more integrated with society and having a greater capacity for identification with and acceptance of other people than the comparison group.

Other studies have found that the  Temperament and Character Inventory output is deeply rooted in genetics, which is quite useful to know for Swedish mothers. The findings were reported this week in BJOG: An International Journal of Obstetrics and Gynaecology.