Comments on: THE EFFECTS OF CRYOPRESERVATION ON THE CAT, Part 2 A revolution in time. Thu, 11 Apr 2013 01:11:28 +0000 hourly 1 By: chronopause chronopause Wed, 22 Feb 2012 23:38:40 +0000 I’m not sure that fixation isn’t a viable approach. It is certainly true that the technology to implement it has not been developed to a marketable state. This may be because there really are very difficult technical and theoretical problems to be overcome, or it may be simply because no one has done the bench work. You can certainly lock up structure homogeneously throughout the brain by perfusing the right fixatives. You need to fix the lipids as well the proteins – unless you can solidify reasonably promptly. However, the REAL issue for stable ambient temperature biopreserevation is to find a way to solidify the system in a timely fashion. This can certainly be done with things like paraffin wax and epoxies – and it can even be done to whole brains and indeed to whole humans, as was demonstrated by the Spanish pathologist Pedro Ara in the 1940s.

The photos above are of the head of Spanish peasant that Ara prepared in the first half of the last century. They have resided for decades in the hot, stuffy Museo de Anatomí Pedro Ara in Cordoba, Argentina. Also in the museum are others of Ara’s preparations, including this striking one of a human head with exposed brain:

Ara is most famous for his postmortem preservation of Eva Peron, the charismatic wife of the Argentine dictator Juan Peron.

There has been a great deal of press and commentary that Ara did not, in fact, preserve Eva Peron, but rather, substituted a wax dummy. Or that he gutted her, as was done to Lenin. This is not the case and the evidence that Peron was preserved intact has special relevance to the issue of ambient temperature preservation, because it shows that the the brain, within the head, can be indefinitely preserved, at least in bulk. The evidence is this anterior posterior skull film made of Eva’s head many years after her preservation:

When I saw this for the first time in the early 1980s, my reaction was, “Aha! He really did do it!” The reason for this is because very, very few people (outside of cryonics) would know what the AP X-ray of a human head/brain would like that had been perfused with a ~15% v/v glycerol solution. The use of a glycerol-based initial flush of the vasculature is unique to Ara’s method (as far as I know) and it is ideally suited to overcome the no-reflow phenomenon in the brain and achieve adequate blood washout and recruitment of closed capillaries in ischemic subjects. In Eva Peron’s case, there was very little ischemia since Ara began perfusion within minutes of her death. Again, these outstanding results are consistent with little or postmortem delay (ischemia).

The truly impressive thing is that he was apparently able to achieve paraffin-impregnation of the brain within the skull. Or, he was otherwise able to achieve stable, long term preservation. It is possible to see more detail in Eva Peron’s brain decades after her death on a plain film X-ray than it is in a 24-hour old corpse with MRI (as an example, gray/white matter differences disappear within hours of death)!

By contrast, Lenin, who was not solidified, and was eviscerated, looks in dreadful condition during one of his recent (and regular) “tune-ups.”:

Yes, Lenin looks impressively preserved when on display:

However, the biological reality is quite different. As an aside and in fairness, I should note that Lenin’s brain, or at least much of it, is indeed in the solid state, since it was sectioned and prepared as standard light microscopy slides using H&E staining. When I visited Lenin’s tomb several years ago, I was surprised at the pungent and all-permeating odor of of formalin and phenol which the savvy visitor can smell as soon as he enters the structure. And it is one incredibly impressive structure – I would rank it with the most impressive of those religious structures I’ve visited: The Vatican is impressive in one way, Lenin’s tomb in quite another…

So, the real work to validate ambient temperature preservation techniques, with or without “chemical fixation,” will be by recourse to the bench – by doing lots of careful experiments. The result will likely be something that could properly be described as “art” as much as science.

And this might well be worth pursuing, if for no other reason than that such preparations should be stable indefinitely – indeed done well, for tens of millions of years – and without refrigeration. Both Eva Peron and Comrade Lenin have long outlasted the then seemingly more durable regimes, institutions, and people who preserved them. That’s quite a lesson, and one we cryonicists would do well to pay attention to. — Mike Darwin

By: Alexander McLin Alexander McLin Wed, 22 Feb 2012 13:42:25 +0000 Er did I really just typed cryogenics instead of cryonics?

Sorry, my fingers were faster than my cerebral cortex.

By: Alexander McLin Alexander McLin Wed, 22 Feb 2012 13:37:40 +0000 Thank you for your analysis. I hadn’t understood that fixation still isn’t adequate for human brains. It’s scary to contemplate the interior of a brain going up in flames!

I’m studying the papers you referred to, and am thinking a lot about planning cryogenics arrangements and my personal hurdles.

The Dora Kent case is a disturbing read, it reminds me that unfortunately that cryogenics still have a long way to go before more widespread public acceptance.

By: chronopause chronopause Thu, 16 Feb 2012 21:20:09 +0000 In light of such wide-spread damage to the body during cryopreservation, it seems to me likely that future successful revival techniques will focus mainly on the brain, preferring to regrow the body instead of trying to repair cryogenic damage.

The same conclusion was reached by a handful of cryonicists circa 1973-4. I was one of them. We thus decided that it was both wasteful and dangerous to haul our cryoinjured, aging and disease ravaged bodies across the decades or centuries for repair and rescue. Our solution was “head only” cryonics (neuropreservation).

Are the studies on the cats on-going or was this completed a while ago?

If you read the paper carefully, you will see that the work was done ~30 years ago. This work was a part of a series of planned studies to delineate the nature and extent of cryoinjury in human cryopatients. The first phase of the study was done using rabbits and was undertaken in Indianapolis, IN in the late 1970s. The Dora Kent crisis in the mid-1980s ( derailed further work. Dora Kent was followed by the cryopreservation of one of the Principal Investigators in 1991, and my departure from Alcor. In the early to mid-1990s, my colleagues and I undertook a study using dogs ( to simulate the application of cryopreservation techniques under optimum condition (e.g., very little ischemia) using 7.5 M glycerol. This study yielded vastly superior preservation and you can see the micrographs and the paper (minus supporting materials and methods data) at this link:

Do you have any thoughts about and their different approach? Clearly with their approach, a full-blown mind uploading technology would be required for successful revival as opposed to molecular repair bots.

To quote Yogi Berra, I think it’s de ja vu all over again. IMO, it is a sign, more than anything else, of the failure of contemporary cryonics to properly dominate this intellectual realm and thus to be inclusive of other good minds who’ve also reached the conclusion that biological structure = identity = redefinition of death = possible indefinite survival. Fixation has been carefully considered by cryonicists, almost since the beginning. It faces three monumental problems not confronted by cryonics:

1) Fixatives are comparatively large molecules which must DIFFUSE into tissues before they can act. Under ideal conditions (no ischemia) this not a problem, because no cell is located more than 100 microns from a capillary ( Once ischemia has occurred, even a period of as little as 10-15 minutes, this distance will be increased by many orders if magnitude in the brain (and in other body organs). Diffusion of fixatives under such conditions is typically not fast enough to prevent autolysis. (See:, and: Medawar PB. The rate of penetration of fixatives. J R Microsc Soc. 1941; 61,46, Helander, KG. Kinetic studies of formaldehyde binding in tissue. Biotechnique and Histochemistry. 1994; 69, 177 -179; Helander, K.G. Formaldehyde binding in Brain and Kidney: A kinetic study of fixation; Fox CH., Formaldehyde fixation. J Histochem. Cytochem. 1985; 33, 845 -853.).

By contrast, thermal diffusion (cooling) is much more rapid. Under ideal conditions, fixation should yield very good structural preservation.However, obtaining those ideal conditions will mean the use of the same costly, complex and logistically daunting procedures to minimize/eliminate ischemic injury now being employed by Alcor.

2) Fixation alone does not yield stable preservation. For that, it is necessary to SOLIDIFY the system. This is typically done by substituting all of the water in the tissues with a chemical or chemicals that can then be plasticized. Typically, monomers, or short chain polymers are used, such as an epoxy (like Epon) resin and then a plasticizer is added to catalyze the polymerization reaction, solidifying the system. Diffusion times for such molecules are very, very long and before they can be introduced, the specimen must be completely dehydrated by prolonged soaking in a solvent, such as acetone or methanol. The Journal of Histotechnology. 1999; 22(4), 317-318. Alternatively, a water driven reaction, such as that used in silicone plastination of human remains for anatomy displays ( a la Gunterr Hagens) may be used. Such a procedure takes weeks or months for an object the size of a human brain and would be very costly.

More to the point, it has yet to be demonstrated that such a procedure is actually workable for an object the size of a human brain; in other words, there is currently no procedure or protocol available that has been demonstrated to work! That is a formidable obstacle, indeed, and that is why there is an “x-prize” type of wager for its development currently on offer.

Most plasticizing reactions, especially those that yield solid, highly stable plastic end products, are exothermic and this means that a large specimen, with an unfavorable surface to volume ratio for heat dissipation (such as an entire organ, like the human brain), may actually reach the ignition point in the interior! Additionally, most plastics are not stable over time and have very active chemistries at or near ambient temperature. A vast sub-discipline exists within polymer chemistry that aims to find ways to increase the stability and durability of plastics and there are many, many journals that chronicle these efforts: I have been a subscriber to some of these for many years (for other reasons) and I am impressed with the dynamicity of the chemistry of most plastics at ambient temperature.

3) You may be more than you “connectome.” In other words, the biochemistry of the neurons and their synapses may be crucial to personal identity. Fixation radically alters the biochemistry of living systems and does so in complex ways we are now only beginning to understand. Many of these changes involve large alterations in the stereospecificity of biomolecules and in their relationship to each other – changes that are not, in principle, necessarily either reversible or inferrable. — Mike Darwin

By: Alexander McLin Alexander McLin Wed, 15 Feb 2012 17:16:47 +0000 In light of such wide-spread damage to the body during cryopreservation, it seems to me likely that future successful revival techniques will focus mainly on the brain, preferring to regrow the body instead of trying to repair cryogenic damage.

Are the studies on the cats on-going or was this completed a while ago?

Do you have any thoughts about and their different approach? Clearly with their approach, a full-blown mind uploading technology would be required for successful revival as opposed to molecular repair bots.