Hi Kathleen:

    Fixed tissue gives better morphology than frozen tissue. Also, 
fixation retards diffusion of substances one might want to localize 
(enzymes, antigens). Snap freezing and subsequent sectioning avoids the 
antigen and enzyme degrading/destroying steps associated with paraffin 
processing.

Geoff

Kathleen Cormier wrote:

> Hello all!
>
> A quick question, why do people perfuse w/ paraformaldhyde then snap 
> freeze tissue, for future frozen sections? For example, for beta gal 
> staining. Is it not redundant? What am I missing?
>
> Thanks for clearing this up!
>
> Kathy
>

-- 
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583; fax: -4029 
mcauliff@umdnj.edu
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