At first I was incredulous that they would make this claim, since it makes it appear they either failed to follow the literature enough to notice other researchers made the remarkable discovery of this system three years ago, or are trying history revisionism to claim that discovery as their own.
But I guess the operative word here is "human". The original research actually gets a small mention in the text body.
Another case of a small but valuable increment of research and nauseating treatment of the same by the spin department I guess.
I heard an NPR interview yesterday, and they were pretty clear that they based this on previous studies done by others that found it in rats. They had to spend 2-3 years figuring out the right technique to test for it in human cadavers, so their work was really in confirming that the same system is present in humans.
> While it was initially believed that both the brain and meninges were devoid of lymphatic vasculature, a recent study by Antoine Louveau and Jonathan Kipnis at the University of Virginia, submitted in October 2014, and another confirming the discovery, by Aleksanteri Aspelund and Kari Alitalo at the University of Helsinki submitted in December 2014, identified and described the basic biology of the meningeal lymphatics using a combination of histological, live-imaging, and genetic tools.
> the team discovered lymphatic vessels in the dura, the leathery outer coating of the brain
Can someone explain why these vessels were never discovered during autopsies until now? Are they too thin, or transparent, or thought to have been something else, or the tubes become squished after death and therefore difficult to separate from other tissue, or what?
Kipnis made a mention of this in an interview closer to the actual discovery:
As to how the brain’s lymphatic vessels managed to escape notice all this time, Kipnis described them as “very well hidden” and noted that they follow a major blood vessel down into the sinuses, an area difficult to image. “It’s so close to the blood vessel, you just miss it,” he said. “If you don’t know what you’re after, you just miss it.”
Then what of the Italian scientist who noted them 200 years ago? All of those dissections and attention to research in the modern age and it was actually taught in medical school that the brain had no lymphatic system? Seems a little far-fetched.
"Then what of the Italian scientist who noted them 200 years ago?"
Two possibilities come to mind. First, he may have been studying a rare brain that had an enlarged system, and since he did not have preconceptions that what he found couldn't possibly be a component of the lymphatic system, he called it like he saw it. (It is also possible such brains were less rare back then or something. Many things have changed in our body's environments in the last 200 years. Random correlations abound.)
The other is that perhaps he was simply wrong. He saw something that he identified as a lymphatic component but was in fact something else. Future people didn't make the same mistake so the observation sank without a trace. 200 years later, the real and much-more-subtle lymphatic system was found.
That reminded me of another example of this I remember seeing in the headlines; I'm not sure if this [1] is the one I'm recalling, but basically this is a similar situation for a different structure in the brain that was discovered in 1881 and then forgotten/ignored and omitted from medical texts for about a century.
Leonardo became obsessed with the heart in the latter period of his remarkable life. He made a prediction about the main blood vessel leaving the heart, the aorta. He had figured out how the flow of blood out of the heart actually closes the aortic valve.
Leonardo had no way of testing it and no way of seeing inside a working heart. For centuries no one else even speculated. But in the last 50 years technology has finally been invented to show that he was absolutely right.
The "they're really close to the blood vessels; you could easily miss them" answers don't make sense. Surely any time you do brain surgery in the area beside those blood vessels, you'd be studying the area minutely?
Anatomy textbooks aren't anything like real life. They're all colourful, clearly distinguished and clearly labelled, yet any autopsy will reveal a mess of reddish brown that tangles and squishes together. Also remember that human bodies aren't constructed, they're grown, so the idealised version of the textbook isn't what you end up seeing when you cut something open, and what you see when you do that changes each time you do that. It's why cadavers are still used to teach medical students.
Who says no-one thought to look? But apparently only one person on record found them before.
How about you have a peek at the research article, think away the colors from the antibody staining and see if you still consider it strange that it could go undiscovered.
The things in question are appropriately measured on a micrometer scale, fragile to match and tightly tangled up with similar things inside jelly. And needless to say they don't come with helpful colored plastic hulls or developer defined object type annotation for inspection.
fta:
In 1816, an Italian anatomist reported finding lymphatic vessels on the surface of the brain, but for two centuries, it was forgotten. Until very recently, researchers in the modern era found no evidence of a lymphatic system in the brain, leaving some puzzled about how the brain drains waste, and others to conclude that brain is an exceptional organ. Then in 2015, two studies of mice found evidence of the brain’s lymphatic system in the dura. Coincidentally, that year, Dr. Reich saw a presentation by Jonathan Kipnis, Ph.D., a professor at the University of Virginia and an author of one the mouse studies.
A few years ago we discovered a new ligament in the knee. Knee injuries that frequently require surgery are so common in children that it's considered an epidemic. I don't really have a good answer to why we don't know about these things, but this isn't the only case of it lately.
I wonder the same thing. Not to be snarky, but is there something faulty about medics or human biologists?! Why do I have a feeling that if we deployed computer scientists at medical research we would get a better result? I can accept that at the lower level things get fiendishly complex, but surely at a macro level like this it's just a case of diligent analysis?
The only difference (from my perspective of course) is comp sci arrogance is directed towards our field and associated methodologies, principles, etc. Doctors direct their arrogance towards themselves.
This generalization is pretty large and may itself be an example of arrogance. But I think maybe it's just the brevity of your comment that gives this impression.
It implies you know what doctors do about as well as you know what comp sci people do, by virtue of comparing the two. The comp sci part is at risk of taking your anecdotal experience as too representative of the whole. The doctor part is (presumably) at risk of relying on stereotypes about doctors having "God complexes" ... So to get to an effective general comparison would be quite difficult without more accurate data. Buuut if we see ourselves as smart computer people, maybe we think more highly of our own inferences than they deserve. I would expect doctors' arrogance has a lot to do with their training and respect for their processes and practices as being highly reliable and advanced. Rather than them personally just having a talent for doctoring.
Most professionals in the field of medicine were educated towards an elitist and dogmatic mindset. When I talk with a physician about the human body I always get the impression they really believe the body works as described in the books - exactly like that. Most of them didn't seem to have noticed or learned that what we know about medicine is just theory approximating reality and all of those theories had to be updated sooner or later - always.
one time i got a sore throat and fevor, the fevor wouldnt break for 7 days. the entire time i could feel the spot where my sickness was coming from. i looked in a mirror and there were puss modules - classic strep throat. I go to the doctor, she does the strep test and it comes back negative, she refuses to prescribe me antibiotics and told me to just go home and rest.
luckily, i had a penicillin script that I didnt finish, and after the first pill the sore throat (and the fever) broke within hours.
later when talking to my brother (who is a doctor), he told me the problem, one that he had also. When he gave the step test, it came back negative even when he knew it was positive. an older attending told him that you have to really get it in there, rub it around for a long time in order for it to work, where most just do a quick swipe.
another such example was someone came to the ER with chest pain. they didnt detect anything in the blood test so they were going to send him home. my brother refused and ordered more tests. turns out he was in the middle of having a heart attack when they were going to send him home, because ... the test.
the moral to the story is, many doctors blindly rely on tests and whats in the book, and disregard contradicting evidence.
Your doc just did the physician equivalent of "closed, cannot reproduce".
Also, shame on you for not finishing your antibiotic prescription. Always finish your antibiotic! If you don't finish, you run the risk of a resurgence of the infection, except this time with bacteria resistant to the antibiotic you failed to finish.
If you really feel like you need a private stash of antibiotic, buy amoxicillin for aquarium fish instead of saving portions of old prescriptions. And make sure you weigh yourself and appropriately calculate the mg/kg dosage before using it.
(I understand that this is hypocritical to shame someone for not finishing a prescription antibiotic and also to recommend misuse of veterinary antibiotics.)
Fyi for a healthy person taking anti biotics for strep has almost no effect (reduces symptoms by like 12 hours) except you stop being contagious much faster. So it wasn't really that critical.
Keep in mind that society has chosen to have physicians carry social and often moral authority. They are the modern priests and priestesses of our secular world.
What stings when a physician is impatient or misses something obvious is the disrespect people feel because of the physician's venerated status. It's as if a person of faith is visiting a Bishop and the Bishop mutters a profanity during the blessing.
The irritation and accusations of arrogance toward physicians that are found in this thread are (if read carefully) reflections of the unique, clergy-like role that physicians play. A physician's opinion can get you decades of workers comp or can deny it to you, it can make you feel responsible for a health problem or vindicated, it can result in the removal of pain or the continuation of it. Physicians let some people get high every day on any number of drugs, declare others bad surgical candidates, and instill (or withhold) hope in those whose life hangs in the balance.
It's a deeply moral role, and the trend toward free healthcare for all is analogous to publishing the bible in languages besides Latin. Physicians are gatekeepers to redemption and this makes some people very angry.
I make the same analogy all the time, but I'm reminded of an old joke[1]:
A mechanic was removing a cylinder-head from the motor of a Harley motorcycle when he spotted a well-known cardiologist in his shop.
The cardiologist was there waiting for the service manager to come and take a look at his bike when the mechanic shouted across the garage.
"Hey, Doc, want to take a look at this?"
The cardiologist, a bit surprised, walked over to where the mechanic was working on the motorcycle.
The mechanic straightened up, wiped his hands on a rag and asked, "So Doc, look at this engine. I open its' heart, take the valves out, repair any damage, and then put them back in, and when I finish, it works just like new. So how come I make $39,675 a year and you get the really big bucks ($1,695,759) when you and I are doing basically the same work?"
The cardiologist paused, smiled and leaned over, then whispered to the mechanic.....
As I said in my comment, at a macro level. I just don't understand how new human anatomical features that are not even at a microscopic level are still being discovered in 2017. It boggles the mind.
I think this may be an example of the Dunning–Kruger effect - when they complexities aren't understood, it's easy to makes assumptions where you simplify to absurdity.
This one, together with the original rodent observation in 2015, is one of the few "macroscopic" observations in anatomy the last decades. Since most of the details of human and higher mammal anatomy have already been described, it is rather rare and outstanding to make such new, remarkable observations.
I'm not a biologist, but can't this type of discovery be made by doing e.g. RNA-Seq analysis of cells in different parts of the body? I can imagine that every type of cell has a unique fingerprint, and lymphatic cells would be easily identified when sampled in the brain this way.
This is very interesting for martial arts practitioners. It's highly plausible that this waste system is the missing link between Parkinson and Alzheimer and concussions due to head strikes. I'd assume that a strike to the head will - if severe enough - first impair the dura mater. This might impair the waste system and by that facilitate inflammations in the long run.
Interesting stuff, though I could have sworn I'd seen something similar before, to do with the waste draining being one of the reasons we need sleep (i.e. the body needs time to drain the accumulated waste products).
Anecdotally, whenever I've had that droopy-eyelids nodding off sensation, when it passes it has always felt like the tiredness is literally draining from my brain.
They don't have a BRAIN but they have nervous system. A nervous system creates waste and that waste needs to be reclaimed. What's a brain? An exotic collection of neurons... that create waste.
>Instead, jellyfish have a ring nervous system, located along the margin of the bell. There is definitely a concentration of neurons in that location (although it contains relatively few neurons compared to other animals). Plus, those neurons do serve as an active relay and processing station for sensory and motor activity. Those are two of the main things that central nervous systems do, so there seems to be no good reason to deny that jellyfish have a central nervous system. (Picture from Mackie and Meech, 2000.)
"As noted by others, sponges lack nervous systems, [...] sponges don't have nerve cells at all. So NO they don't 'sleep" in any manner similar to other animals."
Although I appreciate this kind of reasoning in general, I think it can be misleading when applied to animal behavior.
What prevents one of the reasons we sleep to be absent from the set of reasons jellyfish sleep?
Also, wouldn't it be surprising if a behavior as complex as sleeping had only one reason, or if the main reason today would be anything like the main reason back in the days were the common ancestor between us and jellyfish lived? And so, shouldn't we expect that we sleep for different reasons?
The quote says "one of the reasons". You replied "can't be the reason". There's a fundamental disconnect there: the person you're replying to didn't say that there was any fundamental reason, or that they were describing it.
We don’t need to sleep, but our body will put us to sleep. There is no clear answer as to why we sleep. But one acceptable theory is our brain “understands” sleeping is going to help functioning. During sleep our immune system finally has the opportunity to clean up waste. The 2017 Nobel Prize winners for Medicine and Physiology discovered there are genes famously work as “inner clock”, and they think these genes are responsible for all the routines in our body.
But fundamentally we still do not have an absolute answer to why we sleep, just like we have several theories on why we dream. However, I believe whatever theories exist for why we sleep and why we dream, they are union of a bigger theory, not mutually exclusive.
Lots of disbelief in comments here, having done dissections I think it is entirely believable that a structure this subtle could escape definition. Dissection is not trivial.
Looking at this abstractly, there is a fun quote from Albert Michelson in 1894:
"While it is never safe to affirm that the future of Physical Science has no marvels in store even more astonishing than those of the past, it seems probable that most of the grand underlying principles have been firmly established and that further advances are to be sought chiefly in the rigorous application of these principles to all the phenomena which come under our notice. It is here that the science of measurement shows its importance — where quantitative work is more to be desired than qualitative work. An eminent physicist remarked that the future truths of physical science are to be looked for in the sixth place of decimals."
Albert Michelson is the Michelson of the Michelson-Morley experiment that showed that the speed of light was identical from all perspectives - a discovery that was soon to completely revolutionize our understanding and notion of physics. The comment was also made shortly before quantum mechanics would really begin to be delved into, further revolutionizing physics.
We only know what we know. And that's all we know - until we know more. In the case of the brain in particular we have practically zero causal and holistic understanding. And much of what we do know has been driven by pharmacological profit motive, which doesn't necessarily yield the most objective science and certainly constraints it in any case. Ultimately, I'd be rather more surprised if there are not a vast number of fundamental discoveries yet to be made!
I'm making a comment about gross anatomical structure. Not "where is the seat of consciousness" but "this thing here? its a lymph tube" -thats a single, simple gross morphological observation: tubes have walls. tubes have boundaries.
This is not the only 'how can we not know this' thing which happens, I read a few years back that fundamental nervous system linkages (as in, the actual nerves themselves) of the clitoris had not been mapped in the 20th century because nobody felt like it mattered enough until women anatomists started looking more carefully at the cadavers...
Until we can find where and how consciousness is, and how to define it in the words of science, there will always be more to explore and discover. That's because there will always be pieces of a living system that will elude us, until the final mystery is found.
I agree. I thought we were past that point of figuring out the structural parts. To me, the most interesting things are metabolic pathways, which are incredibly complex, photobiomodulation (effects of eg near infrared light), and electromagnetism (eg electrolyte channels can be triggered by em radiation). But knowledge about this lymph system in the brain could prove SO useful for so many disorders. If eg bodyweight set points are modulated by inflammation in the hypothalamus, would this not in some way be affected by the lymph system?
Haven't read it just replying to the headline. I think it is amazing that how a systemic approach to medicine could affect modern medicine. Defining the boundary and the inputs/outputs are the most important aspect of understanding any system.
I was wondering whether the stuff that this new lymphatic vessels carry were still known to be dumped off the brain by blood or otherwise, or were assumed to remain in or to be used up by the brain.
Can this mean that if one has a lot of stress, then its brain makes a lot of waste which pollute the lymph and thus affects the immune system ? ('cos it's well known that stressed people get sick quicker)
Stress is a factor of hormones and metabolic factors.
Brain has constant metabolic consumption whether awake or asleep. Endocrine functions of brain are carried out by release of hormones directly into portal (venous) systems.
Intracellular adenosine which builds up over the course of waking day may be uptaken by brain lymphatics but would play a small part if they are inside the dura as this states.
In fact, given clearance rate that is suggested from the article by way of position and size, they likely contribute very minimally to any clearance function if at all(unless further discoveries show intra brain lymphatics)
One thing this does seem to suggest is an explanation of why exercise encourages brain health. The lymphatic system only circulates well when the body is in movement, so exercise would help the lymphatic fluid circulate through the brain and thus help "clean" it.
Another case of a small but valuable increment of research and nauseating treatment of the same by the spin department I guess.