Has anyone got a good fixation method for insect gut tissue which has a thick peritrophic membrane. At present I am using 2% paraformaldehyde, 2.5 glutaraldehyde in O.lM phosphate buffer pH 7.2 and a post fix in 1 osmium tetroxide. With this fix the microvilli are not well preserved.
Ian Hallett
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I don't know how thick you mean for the peritrophic membrane, but I've had good results by injecting fixative into the gut lumen and letting it work awhile before dissecting the gut out in fixative solution. This works Cell, 24:751-771 1992. See discussion of preventing midgut cell surface blebbing on p 768 by injecting fix directly into the gut lumen. Good luck.

Jan Ryerse, Pathology, St. Louis University Med School, St. Louis
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Microwave irradiation has been shown to enhance the penetration of aldehyde in insect and plant tissues and to improve fixation of these tissues for LM and EM.
Five references follow:

1. Lindley VA: A new procedure for handling impervious biological specimens Microsc Res Tech 21:355, 1992

2. Smid HM, Schooneveld H, Meerloo T: Microwave fixation of water-cooled tissuesfor immunohistochemistry. Histochem J. 22:313, 1990.

3. Heumann HG: Microwave-stimulated glutaraldehyde and osmium tetroxide fixation of plant tissue: ultrastructural preservation in seconds. Histochem 97:341, 1994.

4. Login, GR, Dvorak, AM Methods of microwave fixation for microscopy. A review of research & Clinical applications. Prog. Histochem Cytochem 27/4:1, 1994.

5> Login, GR, Dvorak, AM The microwave Toolbook. A practical guide for Microscopists. Bosto, Beth Israel Hospital Press, 1994.

glogin@ bih.harvard.edu
Beth Israel Hospital - Department of Pathology
Telephone: 617-667-2034
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