Video Review : How Do Natural Pearls Form?

[Lagoon Island Pearls]

In recent times I've seen this video posted online,

Before commenting, I will disclaim a few things. The video was produced by the SSEF lab and contains beautiful scene work by our friend and pearl farmer Josh Humbert. (and others, if I'm remiss). This review is not intended to take away from the fine work of these industry professionals, but to provide some clarity to a new myth that seems to be generated within the last decade.

Let us start with some background to this concern. For nearly a century, it was put into the public domain that somehow pearls are typically formed by grains of sand. For what reason? The myth seems to be perpetuated from a statement of policy issued by the Mikimoto company nearly a century ago. There it was purported that any foreign object, including a grain of sand may give rise to the onset of natural pearls.

Decades of pearl farming around the world have shown us that nowhere in the aquacultural history of the industry do farmers or their technicians use grains of sand in the process.

Several years ago, our highly respected admin and pearl farmer Douglas posted a video demonstration. I say demonstration, not controlled experiment. As valuable as this presentation is, it's not objective. In that video, our father of pearl manually placed several teaspoons of sand into the visceral cavity of a P. sterna oyster. It was observed over a period of time as the mollusk gathered and expelled for the most part, all of the sand.

Since that video was published, a new myth arose, That pearl onset by sand is a myth. For example (name excluded):

Sad to say, you are perpetrating the myth, yes I said MYTH, that a grain of sand can ever cause a pearl to form. Find out the TRUTH on the Pearl-Guide.com forum!

Let us expand on this by looking at the timeline of the reviewed video.

00:30 - "Natural pearls are rare and accidental formations in wild oysters."

True, but claimed among a narrowly described group... oysters. This is a cultural statement, not a natural one. In nature, pearls are not limited to any single taxonomy. Broadly, cultural shell stock are not Order Ostreidae, nor are they exclusive of other mollusks. Even in China, although shell stock is commonly referred to as oysters, they are true mussels.

00:35 - "As such, their formation is a hard phenomenon to study"

I disagree, vehemently. It's not difficult at all. I've been studying micro-pearls for decades. The one thing I enjoy which most pearl farmers do not, is I can produce natural pearls on demand. Not just pearls either, but changes in "pre-pearl" epithelial behavior. ( I will touch on this again later).

00:51 - "In an oyster, there are specific cells that have one sole role in life, that is to produce mother of pearl. (bolding mine)

Again, I disagree. Epithelial cells are not at all simplistic as suggested. They are highly modifiable. While it's true, each mineral producing cell spends a great deal of it's life producing nacre, these cells may be modified to other duties. Not only can they lay up aragonitic and proteins to build shell, they can also "revert", by producing acids and reclaiming metabolic calcium from shells during times of environmental stress (burial, low salinity etc.) or during quiescence. This is why pearl farmers harvest mainly during winter months, when calcite percentages are at a minimum.

01:03 - "A natural pearl is thought to form by a mantle injury, that may lead to a displacerment of cells."

True, but again an issue of exclusivity. On the pearl farm, grafting can be deemed as epithelial displacement. 100% of all cultural pearls, whether marine or fresh water origins are the result of this, however in nature the incidence is actually quite low. The greater part of natural pearl formation is epithelial modification, not displacement. Though not mentioned in the video, "irritation" is an irritating word. Mollusks do not necessarily get friction rashes, because they do not posses the musculature or dexterity for self-inflicted injury. The correct term is "perforation", where cells are split from each other, but still possess a neurological and vascular connection with each other, hence "bridging" occurs. Mantle tissues are combined to a highly tactile form.and will always endeavor in their creation to form an immediate contact with the shells.

01:11 - "Most pearls form in mantle of the oyster"

While the original SSEF course suggested "all natural pearls are formed in the mantle" was edited to affirm "most natural pearls", I disagree.
Again, if we view this through the eyes of a pearl farmer, it may seem true, but it's not. In mussels, the mantle shares the same space as it's gonads. Not so much as a single organ, but a series of gonoducts which infiltrate the mantle tissues. At a microscopic level, cells are modified by autoimmune disorder, blood borne parasites or muscular hyper extension. Again, several formations in complete absence of displacement.

Natural pearls are not exclusive to the mantle. They also commonly form in the pericardium, extrapallial space, byssal gland, visceral mass, adductor muscles. In fact, if it has a vascular supply and mineralizing e-cells are present, chances are a pearl may form there. Again, these are observations of the cultural realm, not necessarily that of a natural one.

One thing that was completely omitted from this video is the distinction between homogeneic grafting and xenogeneic displacement. In other words, parasites and/or foreign mantle tissue introduced into other species. These create an entire other group of natural pearls. Parasites capable of drilling create external > internal blister pearls. Parasites or foreign objects and yes... the proverbial grain of sand may enter the extrapallial space and be "spray painted" to the shell. Blood borne protozoa may give rise to spontaneous pearl formation, in either mono, poly or anti nuclear ways. Dead parasites may fester whilst trapped in tissues. Either by host epithelial perforation or rarely by actually putting the mantle of the dead creature on "life support" within the vascular system of the host.

01:43 - "After studying hundreds of thousands of pearls, we have never found a grain a sand inside an actual pearl."

This one gets a "WOW!" from me. While this may be the case with SSEF methodology (or it's shortfalls), it certainly is not with my work. I have observed hundreds, if not thousands of grains of sand at the nuclei of natural pearls in multiple species. It is immediately apparent and indeed a direct cause of natural pearl formation, albeit the incidence is low when compared to other onsets.


In conclusion. We need to look at the bigger picture, not just solely through the eye of the pearl farm industry or the labs which revolve around it. In industry we are limited by species and overshadowed by paths of artificial means to an economic end. While some are, most natural pearls have little or no monetary value, but are outstanding examples of the diversity of nature, fingerprints on the health of our oceans whether by acidification, climate change or environmental stress. New medicines and physical health treatments stem from shellfish science.

As a group of experts, we must be mindful of the tenets of science and espouse them objectively and correctly.

I welcome your comments.

 

[CortezPearls]

Hey Dave! Great to have a debate here and would love to have others join in the fun of course.

 

[Lagoon Island Pearls]

Hey Dave! Great to have a debate here and would love to have others join in the fun of course.

Thank you, Douglas. I edited for grammar, spelling and clarity a few too many times and ended up in the mod queue.

I'm in mining limbo while wildfires ravage my province, so I've been revisiting pearl work instead until the rains come and the restrictions are lifted.

That includes some nautilus/ammonite work as well.

 

[CortezPearls]

I remember you were working on those precious fossilized Ammonite pearls Would love to see an update on that subject too.

I hear you...those forest fires have been bad we also had many down here in Mexico, but the rains have finally started, and I hope that will put a stop on these...and I hope you also get rains up there in your neck o' the woods! Heard the temperatures were like ours: in the 40's (Celsius, that is!).

 

[Lagoon Island Pearls]

Heard the temperatures were like ours: in the 40's (Celsius, that is!).

High 40s at that. 47 day after day, 49 on the day the town of Lytton was destroyed.

Lillooet is overwhelmed with evacuees and displaced folks. Fire spread is currently away from the mine, but I'm not inclined to being trapped or starting new fires, so I'll stay at home for the third time in six seasons. It will change eventually and we'll get the work done, barring any other disasters.

 

[CortezPearls]

I am sorry to hear these news Dave...hard to hear about a town just being destroyed. Saddened for your communities and for the Environment.

 

[CathyKeshi]

Very interesting reading, thanks Dave! I was greatly saddened to read about the fires in your area, and the tragedy in Lytton, as well as the effects in Lillooet. Glad you are being safe and cautious; not the weather to gamble on or in; stay safe; the jade will wait for you. Our thoughts and good wishes to our families in Canada.

 

[CortezPearls]

In recent times I've seen this video posted online,
Let us expand on this by looking at the timeline of the reviewed video.

00:30 - "Natural pearls are rare and accidental formations in wild oysters."

True, but claimed among a narrowly described group... oysters. This is a cultural statement, not a natural one. In nature, pearls are not limited to any single taxonomy. Broadly, cultural shell stock are not Order Ostreidae, nor are they exclusive of other mollusks. Even in China, although shell stock is commonly referred to as oysters, they are true mussels.

Sorry for taking forever to start this, been bogged with work...writing new articles for the Pearl-Guide forum (hope you enjoy the new "Mabe Pearl" section BTW ) and writing an article about pearl farming in Latin america and other things I have going have made it difficult for me to read, absorb, think and answer.

And I agree wholeheartedly on this subject you are expounding above, but you and I are Biologists and we know and understand more about the Nature of...Nature! There is more of a continuum than sharpedly marked separations between species or even groups, but taxonomy tries to organize and compartmentalize things to fit more into "Western Thinking" or categorizing efforts. If non-biologists use these terms or expressions it is Ok, I mean they don't have the same training and they are also trying to reach a broader public of Non-Biologists too, so they will use the same language to communicate more clearly, the way people want to be reached out.

There is a reason why we never see technical papers becoming "Best Sellers" even if their content is absolutely accurate: people cannot relate...but then again, it is not the aim of these documents and the same goes for the video: it is meant to a certain group or public.

At least this is what I think, so I don't see it as a shortcoming in any way.

 

[Lagoon Island Pearls]

There is more of a continuum than sharpedly marked separations between species or even groups, but taxonomy tries to organize and compartmentalize things to fit more into "Western Thinking" or categorizing efforts. If non-biologists use these terms or expressions it is Ok, I mean they don't have the same training and they are also trying to reach a broader public of Non-Biologists too, so they will use the same language to communicate more clearly, the way people want to be reached out.

Of course lay terms are fine, but not if the underlying premise is wrong. The video title is How Do Natural Pearls Form? I'm not sure who the target audience is, but it's not natural pearl people. It poorly touches on one aspect of dozens of likelihoods. Does this matter to the average Joe?, definitely not, but the conclusion is incorrect.

The lab has examined tens of thousands of pearls. This is true in the broadest sense, but unreasonable in the narrow. Many are cultural origin, so the point is skewed, if not moot. The remainder were not the result of controlled experiments (destructive or otherwise) to the existence of volcanic substances within biological structures. Instead, inferred as an emergent pattern incidental to other studies.

I've seen millions of people, but I've never seen a murder. Based on this data, it would be a fallacy to suggest murder does not occur. In fact, I challenge the lab (or anyone for that matter) to cite any such research precluding sand. Conversely, I'll contribute specimens, on demand.

A clam, is a clam, is a clam, irrespective of it's species or hemisphere of origin. While there are different rates of occurrence and susceptibility, any mollusk (shell or not) may give rise to natural pearls. There can be no doubt sand is implicated in natural pearl formation, albeit low by comparison.

Yes, we can geek out all day over the heads of others, but as experts, I hold us to a higher standard. This video missed the point, almost entirely.

So long as labs continue to (solely) generate econo-centric certifications based on reverse-analysis of structural and chemical properties in the absence of peri-mortem pathology, there will always remain a healthy layer of skepticism in their methods.

 

[CortezPearls]

I love the point you are making about "I've seen millions of people, but I've never seen a murder. Based on this data, it would be a fallacy to suggest murder does not occur."

But in this case, I would have to say that what is required is MORE DATA. In science we should only present "actual data" (and of course, this is a way is a lie because scientists are people and prone to "fall to the sides", as has happened with Industry tailored-research papers, where you actually get the data and results you want!). Of course, I do not think this is the case.

BUT you do have to think about it...it's a Gem Lab. They CERTIFY gemstones and pearls for a living...would you send an ugly pearl for certification and analysis? Not likely...you send in the finest specimens only! So these labs are mainly working with high to gem grade pearls! And probably not a single one of these were created with sand! Maybe sand does not help produce beautiful pearls! Hence, they are not wrong, based on their data. And I think this is totally fair.

Now, years ago we had the Lab in Granada, Spain, doing research on pearls and they were able to find other interesting sources of pearl producing agents that I had NEVER ever heard off nor read about: Diatoms. Yes, those microscopic algae-like critters. To my knowledge they did not find sand...I never asked Ana Vasiliu, who I corresponded constantly with and sent her samples (I believe you also did?).
Now, their findings had to do with the fact they were using the non-gem grade pearls! Different data because they are working on different pearls, it just makes sense! And this is not a fault of the Gem Lab at all...they are doing "Commercial Science" or "Plain Science" and have been a major driving force behind efforts such as the "DNA analysis of pearls and corals".

So, I understand where they are coming in from.

 

[CortezPearls]

BTW! I was busy looking for this article in my library...I could not find it (I have well over 1,000 digitalized articles in it!) and finally did

This is a review article by Kiyohito Nagai of the Mikimoto Pearl Research Lab in Japan. I believe it is the most complete and comprehensive article written up to date about natural pearl formation (do not be deluded by the name of the article!) under the title of "A History of the Cultured Pearl Industry" Zoological Science 30: 783-793 (2013).

And the author follows ALL THE PEOPLE involved in pearl research since the 1600's, all those that wanted to answer the question of "What makes a Pearl possible???". This is a snip from the article:

And in this case, we clearly see the 1st person to ever use the "grain of sand theory" there... Sir R. Redding in 1688, but from that moment onwards there is no other man of science following up on that lead, and instead we see that most agree on the "parasite theory" or even others. All studies done independently, on various mollusk species all over the world...in a time without internet, emails and FAXes.

Why don't we have any other lead to a "sand-based" production? Because nobody saw any sand in pearls...at least in the species under study and in all those countries and in these several centuries of timeframe. This must mean something.

Now, this does not preclude the possibility of a rare incidence and in a determined environment and for a particular species. Everything is possible for Nature.

 

[Lagoon Island Pearls]

Why don't we have any other lead to a "sand-based" production? Because nobody saw any sand in pearls...at least in the species under study and in all those countries and in these several centuries of timeframe. This must mean something.

Now, this does not preclude the possibility of a rare incidence and in a determined environment and for a particular species. Everything is possible for Nature.

Again, therein lays the "Because nobody saw" fallacy and although Redding et al rejected causation, it's not dismissed. You'll agree this supports low incidence ONLY, There is no burden to prove something does not exist, but outright dismissal cuts us off from our need to learn more and needlessly generates myths, especially when we know them to exist. I have the evidence and it's available to anyone who can use it. I have hundreds, if not thousands of micro pearls with volcanic basalt and/or plagioclase at the nuclei. Let's be truthful here, the industry has no interest in studying this formally or factually. Zero is the number they've contributed to R&D in my ops during forty plus years of doing this. When it comes to nature and the general public, they certainly love to wrap themselves in that flag though. They know what they know, and that's all they need to know. On the other hand, the labs do need to know, yet don't. For that, there can be no excuse.

I
Now, years ago we had the Lab in Granada, Spain, doing research on pearls and they were able to find other interesting sources of pearl producing agents that I had NEVER ever heard off nor read about: Diatoms. Yes, those microscopic algae-like critters. To my knowledge they did not find sand...I never asked Ana Vasiliu, who I corresponded constantly with and sent her samples (I believe you also did?).
Now, their findings had to do with the fact they were using the non-gem grade pearls! Different data because they are working on different pearls, it just makes sense! And this is not a fault of the Gem Lab at all...they are doing "Commercial Science" or "Plain Science" and have been a major driving force behind efforts such as the "DNA analysis of pearls and corals".

So, I understand where they are coming in from.

I'm glad you mentioned the lab in Spain. Ana is an astute colleague and took our work to a whole other level. Our work started with pearls, but we evolved into structures. As farmers we know e-cells can be displaced, but in nature we know e-cells are modified. She was flabbergasted to learn I could produce pearls on demand. Not only that, but in microscopic form, mere hours and days from onset, including adjacent e-cell behavior changes.

So we re-tooled the research to examine soft tissues instead. It started simply enough, by selecting optimal samples and fixing them for shipping and analysis. Yes, we could see the cells, but being fixed observing changes was impossible. Hence we decided to work with live specimens. This got us escalated to the TEM lab. However, given the times, the cost and the effort and lord knows what else, Ana dropped from the radar and the work has been in limbo ever since. She mentioned restarting one time, and I agreed, but never heard from her again. Covid-19 didn't help and getting these things introduced into a curriculum takes years. Funding is non-existent, so I need to do other things to offset the cost. The incidental pearls are a nice reward, but make thin broth.

We did learn other things along the way. We know the mantle is not just a membrane that precipitates mineral rich fluids, instead a highly tactile surface which methodically places pre-formed crystals at precise locations (repeatedly over time). Likewise these (or their adjacent cells) may revert to uptake the same minerals during periods quiescence or environmental stress. The assertion in the video that e-cells have a sole purpose, entirely missed the point.

Using the mabe pearl as an example, does it not seem reasonable to assume that if a plastic object glued to a shell can become stratified by nacre, that the same would occur when sand is introduced into the extrapallial space?

I'll say it again, looking back at natural pearling from a cultural standpoint sometimes needlessly imposes limitations on our ability to learn about the natural world. While we often use generic terms to describe complex nuances, terms like "non-nacreous" are greatly misplaced or misused. The first thing we learned from my pearls that even these so called non-nacreous pearls do indeed possess nacreous structures (both columnar and terraced) between their prismatic and foliated calcitic structures. We know most cultured pearls to be highly nacreous. Lowly does not mean "non". Let's flip the script for a moment. I would be correct in saying I work almost exclusively with non-cultured pearls, but it's needless if not redundant. We try hard to say pearls. We don't say Oh my goodness will you look at that strand of non-natural Tahitians!. How about a blanket thrown over the whole industry for producing non-foliated pearls? It's silly, right? These terms are limiting when used that way, as to elevate the aesthetic quality of structures above other species for their subjective gem qualities. Science does not care what pearls look like. Unlike butterflies or flowers, there's no dependence upon survival or reproduction based on their presentation.

Octopus, squid and nudibranchs are non-nacreous mollusks, but we don't usually describe them as such.

 

[Lagoon Island Pearls]

 

[Lagoon Island Pearls]

Let us examine this simple, yet important terms, one step at a time. We'll ignore interpallial or endo phenomenonal pearls for a moment and consider the extrapallial scenario. Mabe, if you will.

Why is radius x > y?

Would you agree it is a result a void space created between the outer epithelium and the inner valve along the x axis?

Would you agree, the only factor presented here giving rise to epithelial modification/displacement is unoccupied space?

If we were to substitute the geometry and material for say....a grain of sand... what factors would preclude natural mineralization aside from what we discussed in the first two questions?

 

[CortezPearls]

Wow David...yo do touch on too many subjects at the same time that is really hard to keep track of everything and then one has to "select" the "most important" (when they are all VERY GOOD points, and equally important) which is something I would rather not do...but since I do have to do other things (I'm bogged with work this week) I will just have to lightly touch on a few of these points. My apologies for this.

There is no burden to prove something does not exist, but outright dismissal cuts us off from our need to learn more and needlessly generates myths, especially when we know them to exist. I have the evidence and it's available to anyone who can use it. I have hundreds, if not thousands of micro pearls with volcanic basalt and/or plagioclase at the nuclei.

I agree with you, Science has this way of thinking that I believe sometimes works as a "Religion" and "controls what you believe", but then we've had all these times when science is disproven with NEW DATA...just some 20 years ago DNA was considered as unchangeable & deterministic, but then came "Epigenetics" and all of this had to be changed...and still some believe the old knowledge. I once read that once European Universities still taught that our Planet was the center of the University, some 300 years after the Church had agreed it was not!
So, this has always happened...and fortunately, today, people are not being burned alive or stoned to death.

If we were to substitute the geometry and material for say....a grain of sand... what factors would preclude natural mineralization aside from what we discussed in the first two questions?

Nothing would impede the formation of a pearl over sand...except the fact that the mollusk easily displaces it out of its shell by means of mantle movements, mucus productions and inner currents. But, if you were to use some glue...yes, I believe sand would stay there and become a blister pearl. We could make "sand implants" by compressing and attaching sand grains together and then using these to produce pearls...but this is far from being a natural process.

What I see here is that you have a TON OF GREAT DATA, but it has not been published in a peer reviewed article. I believe once you have this it will become a unique moment in the understanding of pearls for Humanity, but this is a pre-requisite for this acceptance...well, because the world is as it is today (and it ain't no different!). Even if you did not have an article...you could write a book! Self-publish it and just hand out this knowledge to all, thus the ideas will be able to gain traction and eventually acceptance. Your name could become associated with the final understanding (something I believe is not possible until we reach the quantum field understanding, but that is just me) of how pearls are produced.

 

[Lagoon Island Pearls]

Nothing would impede the formation of a pearl over sand...except the fact that the mollusk easily displaces it out of its shell by means of mantle movements, mucus productions and inner currents. But, if you were to use some glue...yes, I believe sand would stay there and become a blister pearl. We could make "sand implants" by compressing and attaching sand grains together and then using these to produce pearls...but this is far from being a natural process.

I am glad you mentioned this. While true, it's only true in a very narrow order of it's class, where the mantle can be reflected. This is not the case in Hyriopsis, Unionidae, Margaritiferidae and Mytilid (fresh and salt mussels) and a greater part of bivalvia, the mantle is attached to the shell at the base of the periostracum. Lodged grains of sand have no pathway for sloughing or expectoration when shells become cracked or the mantle perforated. Again, this alludes to my assertion from a pearl culture standpoint only. The way farmed pearl oysters behave is not a perfect analog of how other molluskan species behave in the animal kingdom. Far from it. Those who say this has no bearing on anything economic I might expect, but not from the scientific world. There's a burden that's not being met by the labs. Again, the near complete absence of pathology in their certifications. The evidence is offered, but with no takers. Why? No money?, probably. Willingness?

This isn't new. I've been saying it all along. Several years ago, I posted an image geoduck shell with a bunch of sandy pearls, (I suppose that's searchable). I'm content with debunking the degree common knowledge suggesting where grains of sand are implicated, but that's where it ends.

At the end of the day, why is this even a thing? A new myth does not replace an old myth. Moreover, perplexed why the labs have the optics of going down this road?

What I see here is that you have a TON OF GREAT DATA, but it has not been published in a peer reviewed article. I believe once you have this it will become a unique moment in the understanding of pearls for Humanity, but this is a pre-requisite for this acceptance...well, because the world is as it is today (and it ain't no different!). Even if you did not have an article...you could write a book! Self-publish it and just hand out this knowledge to all, thus the ideas will be able to gain traction and eventually acceptance. Your name could become associated with the final understanding (something I believe is not possible until we reach the quantum field understanding, but that is just me) of how pearls are produced.

Thank you for that advice. Data is great, but data needs to be compiled. I have mountains of data. It's hard enough to get a research assistant to count cells, no less quantitative analysis of an entire field. Stuff like this is hard to teach online to students without biological prerequisites, textbooks and white boards. I draw a lot of diagrams in my lectures and things move along fine. I've tried my hand at 3D animation, but others are better at it.

Pearls aside, the whole climate thing and it's glaring patterns in bio stratigraphy, is something yet again. It's frustrating to see all the good money thrown after bad on that one. A lot of deaf ears there too.

 

[CortezPearls]

Yes, I get your point...I forgot that marine mussels do have their mantle very much "attached" to the shell (unlike Pteriidae) so it could be more difficult for them to get the sand out. We have several species of Mytiliids here in the Gulf of California and I did work (and ate!) with these for years. I even found natural pearls in them.

I only kept one of these...probable cause: parasitic intrusion. It was very evident on the shell, where it was almost attached to, but never dared cut in half to find further evidence.

I understand you COMPLETELY, 100% when you state that data must be compiled, then finally have it become information that can be used by others to back a statement. I suffered from the same ill when working at the pearl farm...sometimes I could not even collect data! Because I had my hands full with just plain ole work!

The way we do things down here is that we approach a Master's degree student with the project, get him involved and then -hopefully- it will work out and he will have a precious paper and will be able to graduate. You end up as the main researcher and you also get the paper. Win-Win situation, but you have to find that particular student, and it is not that easy.

I can only wish you the best of luck in this search for the optimal solution to this issue. It is definitively not easy and without the funds...it's even more difficult since we basically have to "work the grind" daily and that leaves you with little to no time or energy to gather and analyze data, sort it, come up with hypothesis and finally present this information.

 

[CortezPearls]

Minor thread revival due to this article I found over the weekend:
Pearl not result of foreign body reaction in oysters: Andaman-based scientist's latest finding - The Economic Times (indiatimes.com)

The newspaper article (and definitively not a scientific source) basically states that natural pearl formation is not due to reaction a foreign body...because natural shell secretion is constant. Of course! Nacre is deposited constantly (unless the animal is sick or near death) but pearl production -not just shell layering- is indeed caused by an exogenic agent.

This has led to a successful biomineralization process of nacreous secretion in pearl formation in vitro. It reveals that the secretion of nacre by mantle tissue is not necessarily the result of foreign body reaction," he observed.
Further, the research revealed that "when we grow the mantle in vitro, there is no foreign body. The mantle secretes nacre for life time. Now, we know how to induce the mantle to secrete nacre and we also know what micronutrient can be induced to produce major aragonite crystallisation."

And I think your input here would be very valuable Lagoon Island Pearls What do YOU think of tissue cultured pearls???

 

[Lagoon Island Pearls]

Minor thread revival due to this article I found over the weekend:
Pearl not result of foreign body reaction in oysters: Andaman-based scientist's latest finding - The Economic Times (indiatimes.com)

The newspaper article (and definitively not a scientific source) basically states that natural pearl formation is not due to reaction a foreign body...because natural shell secretion is constant. Of course! Nacre is deposited constantly (unless the animal is sick or near death) but pearl production -not just shell layering- is indeed caused by an exogenic agent.



And I think your input here would be very valuable Lagoon Island Pearls What do YOU think of tissue cultured pearls???

This is an interesting article and I'm delighted you've brought this up for discussion, Douglas. I'll cherry pick a few quotes and comment accordingly.

Let's establish terms of reference first. : Epithelial cells in molluscs may be modified and/or displaced to form pearls.

From the article : 'pearl is not a result of foreign body reaction in oyster'

While it's true pearls may form in the absence of foreign bodies, we ought to compare the words "reaction" and "result" for clarity. To suggest reaction, one may assume the chemical or structural properties of the foreign body itself are what initiate the events.

Pretty much any creature in the animal kingdom can survive with little or no reaction from a broad range of foreign bodies. However, the location of these matter. In the human situation, we could agree a shard glass (for example) under the skin may form a tiny bump and any injury would be minimal, however that same material in a joint or organ may give rise to greater problems. Those would be results from different reactions. From that assertion, it can be concluded the reaction was physical, as opposed to chemical. Why the difference? Clearly the adjacent tissue type matters.

This is why the term irritant, irritates me. It's too narrow in scope. After all normal mineral capable e-cells do not appear spontaneously where foreign bodies are concerned. However, granular cells (scar tissue) may form as cysts, nodules or pockets instead. These are not perio or myostracial pearls though. For that to happen, we must have cells which comport with the terms of reference.

For the sake of this part of the discussion, let us presume the reaction is physical and ask how and why. I suppose several reasons are possible, but in all likelihood, it's a vascular thing where supplied blood is restricted or cut off. Pressure may cause a loss of vascular supply, but invariably results in necrosis. It's doubtful this gives rise to pearls. However, perforation is the key word here. As we've discussed earlier in the thread, spaces are created between existing e-cells. When this occurs, new cells divide and multiply to reoccupy void spaces. In nature, it's not unusual for cracks in shells to fix themselves. The same is true in bones of other animals.

To that end, part of the article is correct, but only by one factor. It entirely misses others.

"when we grow the mantle in vitro, there is no foreign body. The mantle secretes nacre for life time. Now, we know how to induce the mantle to secrete nacre and we also know what micronutrient can be induced to produce major aragonite crystallisation."

Again let's revisit the terms of reference. In my previous paragraphs, I've described one form of epithelial modification (we'll discuss another later). The above quote describes epithelial displacement. Two very different things. Modern pearl farmers depend upon homogeneic periostracial transgrafting. For grafts to be successful, we must meet a minimum of two conditions. 1- Compatibility and 2 - Vascular supply. Sections of mantle tissue are placed into genetically identical species. The deftness of the technician can make or break the rate survival which usually may be co-related to vascular supply.

The assertion mantles create nacre consistently is misstated. They evolve to mineralize at different levels. Myo/periostracial > prismatic > nacreous > calcitic. The article misses the point that mantles also de-mineralize at times. This is described as "reversion". All living things need calcium. At times of low salinity, quiescence or buried in sediments, mantles do exactly the opposite. Instead of building shell, they'll reduce thickness to uptake calcium to support soft tissues. This is why pearl farmers generally harvest in winter months, when surface calcite is at a minimum, hence more lustrous nacre.

"tissues remained healthy even after 72 hours in the culture medium. After reaching, the tissues were again sterilized and cut into different sizes to prepare the explants for a series of experiments"

This is a very important point, although the article missed it somewhat. It's true, despite the donor creature being demised, it's tissues remain viable for an extended period of time for the recipient. For obvious reasons this is important to farmers. It allows a window in time to perform a successful graft, but how does this matter in nature? The answer is parasites and their effect on the onset of natural pearls in some cases. Many parasites implicated in natural pearls are either annelids or other molluscs. Parasites do not necessarily need to perforate the mantle to form a pearl. Why is this, particularly when other foreign objects wholly require it? It's because they have mantles themselves. While the parasite may die, it's like we've been saying... the mantle remains viable post mortem, hence becoming a compatible xenogenic periostracial transgraft, provided a suitable vascular supply is present. In this instance, the presence of a foreign body type is absolutely necessary to form a pearl.

This now leads us to other parasites (eg.) blood borne protozoa and/or diseases. Again, in the animal kingdom many creatures may develop auto-immune disorders resulting from infection, especially in the reproductive organs. T-cells become confused, instead of alerting the presence of infection may mistakenly identify otherwise healthy tissue as something they're immune to, hence becoming inflamed. Or in the case of molluscan e-cells... modified to become pearls. This could be summarized as histo-incompatibility, or in other words immunity where antigens and other genetic factors take over, hence anti-nuclear factoring. Immunity is a complex study, but it's probably safe to say multiple etiological factors weigh heavily, as do hormones in these reactions. Conversely, in these instances the presence of foreign bodies at the nuclei are not necessary at all.

Pearls are not exclusive to the periostracial mantle. The adductor muscles are surrounded by a membrane otherwise known as the vestibular mantle. These have little or nothing to do with the overall structure of the valves, but for creating a suitable surface to adhere. This is why I eschew the use of the term "non-nacreous". Even in the overall calcitic structures of conch, melo melo, scallops etc., the structure beneath the adductor is almost always highly nacreous, as are the pearls which form there.

Then lastly, the proverbial grain of sand, other foreign object or parasite within the extrapallial space, in nature. Or the mabe pearl in aquaculture. The one time where "irritant" is an acceptable term for pearl onset. These have very little to do with anything we've discussed preciously, other than merely "spray painted" to the wall, for lack of a better description.

To conclude, pearls result from multiple reasons independent of different reactions in other cases. Therefore when we learn something known to be true, we cannot apply it across the board as such. Genetic diversity is paramount to survival in nature.

 

[CortezPearls]

Hey Dave! Great to have your input on the matter
I knew you would be able to elaborate with utter detail on this article. Just when I finished reading it my mind said: Dave's got to read it and I'd love to hear his thoughts on the matter.