I mean, it&#x27;s not like it&#x27;s a novel procedure or anything.  This is basically how all brains are sectioned for immunohistochemistry.<p>A quick search turned up this protocol, labeled 2006: <a href="http:&#x2F;&#x2F;sydney.edu.au&#x2F;medicine&#x2F;pharmacology&#x2F;CRGweb&#x2F;internal&#x2F;lab_info&#x2F;Fos_Aur=lie2006.doc" rel="nofollow">http:&#x2F;&#x2F;sydney.edu.au&#x2F;medicine&#x2F;pharmacology&#x2F;CRGweb&#x2F;internal&#x2F;l...</a><p>I don&#x27;t know when it was first used, it&#x27;s one of those protocols that every lab has sitting in an ancient three-ring binder.  The procedure is essentially the same everywhere, with minor variations depending on the tissue you&#x27;re working with, the stains, etc:<p>1. Knock the animal out somehow (usually isoflurane or similar)<p>2. Perfuse with Phosphate-buffered saline (PBS) followed by 2-5% Paraformaldehyde (PFA). You can also use glutaraldehyde, which is better for EM, while PFA is usually better for histochemistry<p>3. Rinse in PBS for a while<p>4. Drop the brains into sucrose solutions, let them sit there until they sink.  Usually labs will have a few sucrose baths they like to use (e.g. start in 10%, then switch to 30%).  Sucrose is the cryoprotectant here<p>5. Dunk in liquid nitrogen, coat with OCT, mount on cryostat and start sectioning<p>6. Go about your business staining, etc<p>The only novel thing here, really, is that they perfused the cryoprotectant instead of just letting the brains sit in it for a few days.  Letting a rabbit brain soak up sucrose likely takes longer than a mouse, so perfusing would definitely speed up that step.<p>But it&#x27;s a rather moot point, since fixed brains can chill in refrigerated PBS for a month or two.  There&#x27;s no rush once it&#x27;s fixed ... that&#x27;s the <i>point</i> of fixing.  I&#x27;m with the other folks, this was really just a grab at some money imo.  And fancy headlines.  There is nothing interesting here.<p><i>Credentials: worked in neuroscience wet-lab for 5 years.</i>