7/22/98

What do you do with floating lung tissue (>2mm) that is fixed

by immersion. The options are:

1)leave in a refrig overnight until

they sink (swirling did not work).

2)place in a vac (15 psi) while still in

the fix.

3)process the floating samples hoping

they eventually sink.

I am currently in the frig (opting for #1) but any hints or

suggesstions would be welcome. Thanks.

MICHAEL DELANNOY

delannoy@welchlink.welch.jhu.edu

Take a 2-hole stopper (or make one if you can't find one), and put the wide

end of a cut-off pasteur pipette, or a length of glass tubing, into one hole.

Choose a size of stopper which will seal the top of the container you're

using for the fix. Use tygon tubing to connect the glass tube to house

vacuum, or connect it to a similar device made with a one-hole stopper

which fits onto a side-arm flask--this will prevent any oil in the line

from getting to the sample. Turn on the vacuum, seal the fixing container

with the two-hole stopper, place your thumb over the empty hole until the

residual gas emerges from the tissue, then release the pressure. Repeat

until the gas has escaped from the tissue. Note that the one-hole and

two-hole stoppers can be interchanged, so if you have to hold the stopper

onto the fixing container, it can be better secured if you don't have to

worry about rocking the device with your thumb.

William Tivol

tivol@wadsworth.org

lung. You did not specify whether embedding will be for LM or EM. If

plastic embedding for EM, >2mm is too thick and they should be sliced to

not exceed 2mm. Other dimensions are not important as long as they will

fit in an upside down Beem capsule with the pyramid end cut off.

First put them under vacuum in fix to pull out the air (the tissue will

still be at the surface while in the vac) which will optimize contact of

fix with tissue (I interpret your term immersion to indicate that the

tissue was not first perfusion fixed or insufflated with fix).

Then they can go in the fridge or stay at room temp and should sink.

They will definitely sink during subsequent steps with osmium and

acetone dehydration for TEM.

My experience does not extend to paraffin processing of lung.

Tom Christensen

Pathology

Boston University Medical Center

Tom Christensen

tgc@bu.edu

Email: David.Patton@uwe.ac.uk

"University of the West of England"

A friend had this problem with plant material. She kept

the samples submerged under a piece of wire mesh.

Mike,

Place gauze over the top of the fixative and tissue, this prevents the

tissue from rising to the surface and drying out.

Palatsides, Manuela

m.palatsides@pmci.unimelb.edu.au