[QUOTE=Mynn]
But this popular summary and the study’s abstract made me wonder if persuing a means of preserving this placenta, formally or informally, for later study, might be of some use to us or others later on.
…
Assuming we can’t get our hands on formalin and the necessary preservation materials (either for the entire organ or bits) as ‘civilians’, can it be frozen until/if we can gain hold of these materials, or find a company who can preserve it in observable format for later study, if not for something along the lines of the autism study above, but other research?
I know preservation is done (has been done for folks I know with known issues) … I guess I’d have to look more towards temporary preservation until I can secure agreement from a company to do such a user-requested preservation. Or would freezing it pretty much negate any future chemical preservation usefullness (by the freezing process destroying some of the structure we want to preserve, for example).
[/QUOTE]
I haven’t tried freezing placentas. If you get them down below -70 (which usually takes a scientific freezer) you can keep them for many years without any rot setting in. (I learned this on the Straight Dope, incidentally, but it explained to me why our specimen freezer at work is -70.) When you unfreeze them and section them and stain them, there will be some artifact from the ice crystals, but any decent pathologist ought still to be able to read the slides.
This is what I would do with a placenta. Start with it intact on a clean board covered by a cloth. Have water nearby with a sprayer head. Have a camera, a clean scissors (dip it in the formalin), a clean long sharp knife, a scale that weighs in grams, a measuring tape (ideally in cm), and rubber gloves. Have a half gallon of 10% formalin in a plastic bucket with a top that seals. Assistant nearby writing things down.
Put on the rubber gloves.
Find the rupture point of the membranes (they will look like a circular veil; the opening where the bride puts her head in is the rupture point). Wash the blood off with plain water and photograph the membranes. They should be glistening and transparent without any green or yellow opaqueness. Take a knife and cut a rectangle of membranes from the rupture point to the edge of the placenta. Roll it up and throw it in the bucket.
Cut the membranes off at the edge of the placenta with the scissors. Either discard them, or wash them off and toss them in the bucket. (Free blood combines with formalin, and inactivates it. A dense red formalin fluid almost guarantees bad preservation.) Photograph the placenta from the fetal side (umbilical cord) and the maternal side (blood clots). Peel the clots off the maternal side, weigh them, have your assistant write down the weight. Wash off the maternal side and photograph again.
Check where the cord goes in: 1) in the middle 2) not in the middle, off to one side, but not at the edge 3) at the edge 4) doesn’t even reach the edge - in the membranes. 1) and 2) are both normal, with 2) the commonest by far. 3) isn’t good, and 4) is bad. Measure the length of the cord. If you only have an inch measuring tape, multiply the results by 2.54. Assistant writes it down.
Cut the cord off the placenta. Cut it up into little bits (not all of it; cut it eight or ten times and cut a little bit off each segment end). It is remarkably hard to cut a level round off the end of the cord, because it wiggles and because it is spiraled. Throw the little bits into the formalin bucket.
Weight the placenta and have your assistant write its weight down. Measure its length by width by thickness and write those down. Record the birthweight of the baby next to the placenta weight (the ratio of the two is important - the placenta should weigh just about a seventh of what the baby weighs; more or less means sicknesses).
Slice the placenta up from one edge to the other, all the way through, in slices no thicker than your little finger. Turn them on their sides and photograph them, far away and close up. Any areas that look different, pay special attention to those; the whole thing should be as homogenous as a steak.
Wash the slices well to get as much blood out of them as you can. Throw slices into the bucket until its formalin starts to turn a faint red. Make sure you get one slice from where the cord went in, and another slice from the edge, any slice from an area that looked weird, and as many more slices as you can put in without using up the formalin.
Seal the bucket and throw away the rubber gloves. Bury the rest under a tree or in the garden as you please.
Put the formalin bucket into a thick plastic bag (to prevent slow loss of liquid) and put it someplace safe high up where no child will get into it. Check it once a year; add more formalin as the level declines. If you ever need it examined by a pathologist, a record of what you did, plus the photographs, plus the weights and measures, should be more than adequate.
And if it’s not, I’ll look at it myself.
[/fangirl gushing]
Thanks again.