Slam freezing.

From:"Dr. Ian Montgomery." <>

<html> <x-tab>        </x-tab>Just been reading the posting by Phil and the answer by John. Slam freezing, couldn't be easier and all with home made equipment. <br> EQUIPMENT:<br> <x-tab>        </x-tab>Solid copper rod, 2x3 inches. Get your workshop to polish one end. Then sit with fine paper and polish to a near mirror finish and finish with metal polish. A friendly EM Unit is handy, they usually have polish for the Wehnelt cylinders. Then attach the polished block to an insulated rod or if you can find one, a racket that you can wind up and down.<br> <x-tab>        </x-tab>Bamboo sticks, barbecue type. Buy a pair of Sorbothane insoles then with a punch cut out pieces with a similar diameter to the  bamboo sticks. Glue the Sorbothane cores to the bamboo sticks.<br> <x-tab>        </x-tab>Millipore filters, or similar, cut into small pieces.<br> METHOD:<br> <x-tab>        </x-tab>1.) Fill a wide mouth dewer, almost to the top, with LN2.<br> <x-tab>        </x-tab>2.) Place the copper rod into the dewer and leave to cool. Topping with LN2 if necessary.<br> <x-tab>        </x-tab>3.) Dissect out the tissue and cut into small pieces under a suitable Ringer solution.<br> <x-tab>        </x-tab>4.) <b>Quickly, </b>place a piece of tissue onto a moistened filter then on top of the Sorbothane.<br> <x-tab>        </x-tab>5.) <b>Even more quickly,</b> raise the copper block <b>just out</b> of the nitrogen, then with one even movement slam the tissue against the polished surfaced.<br> <x-tab>        </x-tab>6.) Transfer to a pot of LN2 and cut of the Sorbothane core. <br> <x-tab>        </x-tab>The frozen tissue can now be sectioned or freeze substituted and embedded for sectioning.<br> NOTES:<br> <x-tab>        </x-tab>1.) Keep the level of LN2 high thus avoiding pre-cooling and freezing.<br> <x-tab>        </x-tab>2.) Only bring the copper block just out of the LN2 and only before you are going to slam. Any longer than necessary and frosting will occur, a real bummer. <b>You must have a polished surface.<br> <br> </b><x-tab>        </x-tab>I've used this technique and published the results for many years. Once you perfect the skill it's really easy. Using this technique my lab has produced some stunning electron micrographs from freeze substituted tissue. I've even got one on the wall at the back of my computer, now is that not sad.<br> Ian.  <br> <x-tab>        </x-tab>  <br> <x-sigsep><p></x-sigsep> <font color="#0000FF">Dr. Ian Montgomery,<br> West Medical Building,<br> University of Glasgow,<br> Glasgow,<br> G12 8QQ.<br> Tel: 0141 339 8855.  Extn:6602.<br> Fax: 0141 330 2923<br> e-mail:</font></html>
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