Re: How long are subbed slides good?

From:Gayle Callis

I always understood anything that is considered a plus charge slide was either

1.  Silane coated
2.  poly l lysine coated

These should be used with pure distilled water in waterbath, never adding
any gelatin or gelatin subbing solution which would coat over the plus
charge, so that the gelatin is substituted for a tissue section, as Patsy
correctly states and negates the plus charge, however, the gelatin might
still act as the glue!   Directions in Plus charge slides boxes tell one
how to use the slides, at least Erie Scientific slides do this. 

Subbed slides always meant chrome gelatin. What can make a difference in
how the gelatin subbing works, is the size of the gelatin molecule.  Most
gelatin subbing solutions contain a smaller molecule gelatin, 100 bloom or
less.  For difficult sections, large decalcified bone is prime example, 275
or 300 bloom gelatin can be substituted (made from swine skin collagen!)
and has extra holding power.  Downside, background staining can increase
with larger bloom gelatin. 

Try the larger bloom gelatin to see if this will make a difference.  We
used this for midsaggital sections of distal tibia from sheep, never lost
the sections but they were dried flat in 37C oven for several days, one gal
dried her bone sections for 2 weeks. 

Have kept gelatin subbed slides in a cool, dry box for years without
problems but did use the larger bloom gelatin.  275 bloom was our favorite. 


Gayle Callis
Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367
406 994-4303 (FAX)

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