I don't do this anymore, nor for 40 years now, but this is what we used to
do aeons ago.
1. Fix in 10% NBF for 48 hours.
2 Rinse off excess with tap water for 1 minute.
3. Select pieces of tissue with maximum dimensions of 2cm x 1.5 cm x 0.3 cm.
4. Place into cassettes if you have them, then into a large container. If
you do not have cassettes, place into small jars, each case in a different
jar. Place a label in each cassette or each jar with the case ID.
5. Cover the tissue or cassettes with 70% ethanol, methylated spirits or
isopropanol, agitate gently. Leave overnight.
6. Next morning, replace the 70& alcohol with 85% alcohol, leave for the
day, agitating gently periodically.
7. Before leaving in the evening, replace the alcohol with 95% alcohol,
agitate gently and leave overnight.
8. Next morning, replace the alcohol with 100% alcohol, gently agitate
periodically. Repeat at noon and before you 9. leave for the evening,
10. Next morning, replace the alcohol with clearant, preferably xylene or
toluene. Leave for one hour, gently agitating periodically.
11. Repeat the clearant twice more, agitate gently.
12. Place into premelted paraffin wax for 1 hour at 65C. Check periodically
and when all congealed wax has remelted, agitate gently.
13. Repeat at least twice more, preferably under vacuum - not too strong.
Some technologists used to leave the final change overnight. Doing so
doesn't do much harm and improves penetration. Agitation can't be done
under vacuum, so release the vacuum periodically, agitate and reapply it.
14. Block out into molds. (If you do not have molds, use a metal - tinned
steel or aluminum - lid with a depth of 1cm. LIGHTLY coat it with glycerol
first.) Place a thin (3mm) layer of hot wax in the mold and place the
tissue, with the surface to be sectioned down, into it. Top up the mold
with wax so there is at least 2-3 mm wax over the top of the tissue. Put
the ID label conspiciously next to the tissue. Do NOT block out more than
one tissue or case without placing the ID labels, this WILL lead to serious
identification errors. Do all this by the oven and keep the door closed as
much as possible. Work fast so that the wax around the tissues does not
begin to congeal as that causes problems during sectioning and floating out.
You must get the wax around the tissue and the wax in the mold to blend
completely, so if the wax congeals around the tissue, leave it to remelt
before blocking out. Many of us used to keep a bunsen burner alight and
flame the top of the molds to keep the wax molten - a practice probably
considered unsafe now.
15. Allow the wax in the mold to skin over thoroughly, then GENTLY lower
into cold tap water to cool.
16. When completely cold and solid, use a heavy knife to score and trim the
17. To section, melt the trimmed block onto the block holder.
----- Original Message -----
From: "Merced Leiker"
Sent: Tuesday, September 09, 2008 1:54 PM
Subject: [Histonet] Manual Paraffin Embedding
> Does anyone process and embed tissues manually instead of using automated
> and expensive equipment? Can you tell me how you do it? Thanks.
> Histonet mailing list
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