Advice on sections please

Advice on sections please

Postby Ian Knox » Wed Jun 01, 2011 6:35 am

Hello

Does anyone have any tips on takng sections, is the use of a microtome advised.

I have just joined ABFG and after many years taken the plunge and purchased a microscope, I have taken some sections for the microscope as advised in Identification of the larger fungi by Roy Watling but was wandering if any one had personal tips or methods and if anyone can advise if a microtome would be of use, I have made a crude microtome and tried mounting a section to be cut in wax but the wax seems to affect most of the specimen.

Thanks in advance

Ian Knox
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Re: Advice on sections please

Postby admin » Fri Jun 03, 2011 10:10 am

Ian

Sorry nobody is responding at the moment. This is a very 'low' season for fungi, especially since it has been so dry, and probably few people are visiting the Forum. I think you may be barking up the wrong tree with trying to embed and section fungi. From long and bitter experience as a former professional microtomist, it is extremely difficult to achieve this without massive distortion. What you need to be doing is taking very small 'chunks' of tissue (1-3mm) from either gills, cap surface, or stem etc. and macerating them in KOH - not so much as to completely dissociate the cells, but in order to loosen the tissue elements and be able to make an effective squash under the coverslip. Use a general stain like Congo Red to start with.

There are some good articles in past Forayer issues on the subject, and its worth looking at the microscopy images sent in by people like Chris Johnson to the 'What Is it?' forum to see the sort of results needed.

MJ
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Re: Advice on sections please

Postby Leif Goodwin » Fri Jun 03, 2011 11:31 am

Hello Ian, I will add a few comments to those from Michael. Bear in mind that I am no more than a keen amateur who has worked out some methods from trial and error, and reading comments online. As Michael says, you don't need a microtome. The important point is to get small or thin pieces of tissue. The easiest way for very small fungi (1mm across) is simply to crush the specimen, a so called squash. You can crush between two slides, then remove one slide, though you end up with all the bits mixed together. If possible it is better to pull off tiny bits using tweezers, ones with sharp tips are ideal. That way you know exactly which part of the specimen you are looking at! Here is a link to some useful information:

http://www.fungi4schools.org/Reprints/M ... cimens.pdf

Alternatively you can use a sharp blade to create a section. You need steady hands, and you might need to have quite a few goes before you get a good section. A razor blade will do, but I prefer to use a good kitchen knife. I use a Japanese kitchen knife which has a more acute blade angle than Western knives, and after sharpening it is razor sharp. It goes without saying that these knives require care as they are nasty little devils.

As Michael indicates, Congo Red is an excellent stain. Buy the powder and mix in ammonia solution. The latter is sold as household ammonia in many hardware shops and chemists. Melzer's Reagent is also invaluable and available from the ABFG, to members only as it contains a controlled substance, and you MUST NOT distribute it to others for legal reasons. You will need some pipettes, plastic ones are good, and a jar in which to place the pipettes to keep the stains away from the table and carpets etc.
Fungi and Nature Photography: http://www.leifgoodwin.co.uk/Fungi/Fungi.html
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Re: Advice on sections please

Postby Ian Knox » Fri Jun 03, 2011 12:33 pm

Hi

Many thanks to you both I will be having a practise on a few shop bought mushrooms, I have already purchased a selection of chemicals through ABFG and any further tips or advice again gratefully received.

Another good link I have been looking at is the Scotish Fungi website which has a microscopy section:-

http://sites.google.com/site/scottishfu ... icroscopic


Regards

Ian
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