Messy brown fluid from pig's liver, is it bile?

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The discussion centers on the identification of a dark brown fluid observed during a fetal pig dissection, which was initially questioned as bile. It was concluded that the fluid was old blood resulting from a poorly preserved specimen rather than bile, which can be yellow, brown, or green. The participants emphasized the importance of proper preservation techniques, noting that fetal pigs are commonly used in dissection labs due to their status as by-products of the pork industry. Additionally, the conversation highlighted the necessity for proper ventilation and safety measures when working with preserved specimens.

PREREQUISITES
  • Understanding of fetal pig anatomy and dissection techniques
  • Knowledge of preservation methods for biological specimens, including paraformaldehyde
  • Familiarity with the implications of using fetal pigs in educational settings
  • Awareness of safety protocols in biological laboratories
NEXT STEPS
  • Research the effects of different preservatives used in biological specimen preparation
  • Learn about the anatomy and physiology of fetal pigs for dissection purposes
  • Explore the ethical considerations surrounding the use of fetal pigs in education
  • Investigate alternative dissection methods, such as using frozen specimens
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Biology students, educators conducting dissection labs, and anyone involved in the ethical considerations of using animal specimens for educational purposes.

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We just started dissecting fetal pigs today in Biology, and when I was cutting the abdomin open to get at the organs, I accidentally cut the liver a bit without knowing. By the time I'd completely exposed the abdominal cavity, the entire thing was filled with some dark brown liquid, roughly the color of feces and a bit thinner than A1 steak sauce. My biology teacher has something seriously wrong with him, and when I asked "Is this bile?" he said "Sure, why not?" without actually looking at it. So was it bile? Could that much bile be stored in the liver? I only cut it about 3 or 4 milimeters into it and maybe a centimeter long, so it seems weird that this much stuff would come out.
 
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Bile fluid can be either yellow, brown or green.. it could've been venous blood too or maybe feces from the small bowel (well, not in a fetus). Did you try looking up the gall bladder to see how large it was?
 
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As I recall (I may be wrong) the gall bladder was pretty large, just under 2 cm long and about 70mm wide at its widest point. Of course, I could have been looking at something completely different, and those measurements were just from memory, so they could be off too.
 
No, it's not bile. It was a poorly preserved pig, and the brown, icky stuff is old blood that didn't flush out with the fixative. Run it under gently running cold water to wash it all out, set it on its "belly" for a few minutes to let the rest of the water drain out of the incision, and you'll be all set. I can't believe your teacher just dismissed the question with "sure, why not" without even looking! This is why people end up not learning biology right, because some teachers just can't be bothered to give a proper answer. Oh, and the blood probably didn't originate from cutting through the liver, even if you hadn't hit the liver, you'd have found it filling the abdominal cavity...when they inject the latex into the veins and arteries (so they'll be pretty pink and blue for you), some of the vessels rupture and you get either the blood in the cavity, or if you're really unlucky, you get a pig with a belly full of latex...those are horrible to dissect and you can be pretty sure you're not going to be able to identify all the blood vessels or rely on them being the color they are supposed to be. Also fun when someone switches the colors of the latex going into arteries and veins and all the color-coding is backward of what your lab manual tells you it should be.

Um, yeah, I've taught a "few" pig dissection labs...there are all sorts of fun oddities you come across aside from the usual anatomical variation you're supposed to see. If you think it's hard identifying organs in the pig you're dissecting, it's much harder identifying organs in a pig someone else is dissecting...especially when the ones that are supposed to be in the pig are already somewhere out on the dissection pan. It's all fun though. Just eat a good meal before class and make sure they keep the windows open or have you working in fume hoods so the paraformaldehyde odors don't overwhelm you (for people prone to low blood sugar, something about those fumes can trigger fainting if you don't eat before class...it's really not just squeamish people...you shouldn't have to breathe those fumes anyway).
 
Moonbear said:
No, it's not bile. It was a poorly preserved pig, and the brown, icky stuff is old blood that didn't flush out with the fixative. Run it under gently running cold water to wash it all out, set it on its "belly" for a few minutes to let the rest of the water drain out of the incision, and you'll be all set. I can't believe your teacher just dismissed the question with "sure, why not" without even looking! This is why people end up not learning biology right, because some teachers just can't be bothered to give a proper answer. Oh, and the blood probably didn't originate from cutting through the liver, even if you hadn't hit the liver, you'd have found it filling the abdominal cavity...when they inject the latex into the veins and arteries (so they'll be pretty pink and blue for you), some of the vessels rupture and you get either the blood in the cavity, or if you're really unlucky, you get a pig with a belly full of latex...those are horrible to dissect and you can be pretty sure you're not going to be able to identify all the blood vessels or rely on them being the color they are supposed to be. Also fun when someone switches the colors of the latex going into arteries and veins and all the color-coding is backward of what your lab manual tells you it should be.

Um, yeah, I've taught a "few" pig dissection labs...there are all sorts of fun oddities you come across aside from the usual anatomical variation you're supposed to see. If you think it's hard identifying organs in the pig you're dissecting, it's much harder identifying organs in a pig someone else is dissecting...especially when the ones that are supposed to be in the pig are already somewhere out on the dissection pan. It's all fun though. Just eat a good meal before class and make sure they keep the windows open or have you working in fume hoods so the paraformaldehyde odors don't overwhelm you (for people prone to low blood sugar, something about those fumes can trigger fainting if you don't eat before class...it's really not just squeamish people...you shouldn't have to breathe those fumes anyway).

Thanks for the explanation.

According to my teacher, no form of formaldehyde is used anymore, it's all alcohol now since formaldehyde was found to be carcinogenic.
 
Nope, they are still intially fixed in paraformaldehyde, but then once the tissue is fixed, they are stored in other liquids to flush out the excess paraformaldehyde. There is still paraformaldehyde in the tissue, not a lot, but I would still recommend a well-ventilated area for working with them.

Here's info from a supplier:
About Our Preservative
It is a nontoxic, nonirritating, slightly scented preservative which is much less toxic than formalin. However, we do recommend the use of gloves and goggles as with any chemical. After fixation, in a standard formaldehyde solution (3.7%), specimens go through a soaking and leeching process which removes all but trace amounts (.5% - .9%) of the free formaldehyde from the specimen.

About Our Packaging
Pail Packed specimens are wet packed in our preservative. This packaging is more convenient for specimens to be stored in and out of, but is more expensive because of packaging materials & shipping weight. Vacuum Packed are packed in one or more Mylar bags. These are less costly, but extra care must be given to keeping the specimens moist once the seal is broken. Specimens do not require refrigeration.

Some other preservatives are used, and you can check this link for information about those as well as formaldehyde levels remaining after the "leeching" process. http://cheminfonet.org/spec1.htm
They mention one preservative that contains propylene glycol and phenol...phenol is really nasty stuff too, and I'm not sure how it acts as a preservative. There's another one listed that is called Carosafe, but according to that site, there is no MSDS for it because it's considered "nontoxic"...that worries me since you can get an MSDS for water if you want one...I want to decide for myself how nontoxic something is! I know we required our techs who handled the specimens fresh out of the barrels every day for a week to wear gas masks in the storage rooms, and until they rinsed off the pigs before distributing them to the students. There was a distinct odor of paraformaldehyde in those rooms.
 
I'm really surprised that it was a preserved pig, I would never have guessed :) The only time I worked on an animal, it was a mouse, and they all came to the lab alive :S
 
Oh, Monique, technically, they are preserved fetal pigs. They are very commonly used in dissection labs in the US. They are more "politically correct" than other choices of animals for dissection because they are a by-product of the pork industry. It's not uncommon for sows to be sent to the slaughterhouse while pregnant (either unknowingly, or because the farmer is trying to cut back on the size of their herd), so the fetuses would just get thrown away. So, instead of specifically breeding animals for dissection, they use ones that would have just gone to waste and make use of them. The other "politically correct" animal used are cats that were euthanized for humane reasons. I think these are okay for advanced labs, such as at college level, but think they get more complicated for high school labs. They are a good substitute for someone who can't work with the pigs due to religious reasons (that's the one non-PC aspect of using the fetal pig, observant Muslims and Jews are not permitted to touch pigs or pork. The reason cats aren't as good is that because they are euthanized for humane reasons, they often have some really odd things wrong with them. It's great if you're at a level where pathology becomes an interesting part of the learning, but it just complicates things more when someone is trying to learn basic organ systems and there's a tumor growing on them distorting the shape. Plus, people are more squeamish about dissecting cats because they associate them with being pets.

I have taught college level labs where we chose to use frozen rats rather than preserved anything. You can request the retired breeders from suppliers. Borderline on the PC-scale...they were bred for a company that only breeds animals for research purposes, but the ones used are the ones that would have been euthanized and just incinerated otherwise. There were a few other advantages to using those. First, no preservative. If you can do the lab in a single session, that's a good option, but wouldn't work well for someone doing their first dissection ever who needs several days of dissections to get through all the systems. Second, the tissue has more of the feel of live tissue than a preserved specimen does. Third, not as many people are squeamish about dissecting a rat as long as it's dead before they have to get near it (some think the pigs are cute). Disadvantages, besides that they don't last very long, are that rats are small, so someone doing a first time dissection or who doesn't have steady hands is going to have a tough time with it. There's the necessity of thawing the rats ahead of the lab, and when you just forget to do it early enough, the lab sink full of lukewarm water and dead rats to finish the thawing in time for the lab.

There's always a lot of debate whether dissections are necessary. I'm somewhat undecided about it at the high school level. I think it becomes more important at the college level when the next dissection many of those students will do is the cadaver in med school, so if nothing else, acquiring the skills for dissection and a basic understanding of how the real animal differs from the pictures in the book are necessary at that level. At the high school level, they still make the argument that the dissections are needed so students see for themselves the natural variation in organ systems, which would be great if they ever emphasized that or expected them to look at the animals other groups were dissecting. I don't think this point gets made well, and when your real teaching objective is familiarize the students with all the organ systems, I think just demonstrating the dissection on one animal would be sufficient (I'm not fond of using videos, I think that would just be the time when students fall asleep...not that the videos wouldn't show what needs to be show at that level, but that a video is a very boring way to learn). At college level, then I think the variation becomes an important part of the lesson, particularly when you are teaching students who intend to become scientists. The biology majors and pre-meds definitely need the hands-on experience.
 
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Hi folks

I apologise for reviving an old thread but I've done a fair bit of searching and this is the best place I've found to ask my question. You seem to know a lot about pigs' livers, Moonbear.

I dissected a pig's liver today (for culinary purposes, I'm not a scientist) and as I was removing some unappealing fatty-looking bits an orangey-yellow liquid came out of them. I've never seen this before. Please can you tell me what it is? Is it indicative of a disease? And more importantly, is the liver safe to eat once the yellow gunk has been removed? The vast majority of the liver looked perfectly "normal".

Thanks in advance for time and any answers I might get.
 
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I never worked with liver (in the lab or the kitchen). I would ask the local butcher, they must have a lot of knowledge on the quality of animal products (unless someone here can answer the question).
 
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Many thanks for your answer, Monique. It wasn't possible for me to ask the local butcher at this time so I continued to search. The most likely scenario is that a part of the gall bladder had been included with the pre-packaged liver from the supermarket.

Sorry to have bothered you but I was worried about what it might be, and keen to find out the answer. It was kind of you to reply. I'll get out of your hair now and wish you all the best. Thanks again.