Osmium Only Fixation: by David Hall

1. Wash animals in M9 buffer and chill to 4°C

2. 0.5% Osmium in 0.1M HEPES, pH 7.4 + 0.14M sucrose, 4°C [CUT OPEN IN FIX ASAP WITH RAZOR BLADE]. After 30 min. allow samples to warm. Total Fix time is 120 min.

3. Wash in 0.2M HEPES buffer, 0.1M NaAcetate

4. Stain in 1% UAc in 0.1M NaAcetate, pH 5.2, r.t., 60 min

5. Wash in 0.1M NaAcetate, 2 X 5 min; wash in 0.2M HEPES, 2 X 5min

6. Embed cut pieces in 3% agarose, positioning worms into clusters; allow to harden at 4°C for 1 hour, or overnight under buffer.

7. Cut out small agarose blocks containing worms; should be large enough to be excluded from pipette tip, but small enough to fit into embedding mold

8. Dehydrate through ethanols; 1-5 min in 30%, 1-5 min in 50%, 1-5min in 75%, 2-5 min in 95%, 3 X 10 min in 100% ethanol, 3 X 10 min in propylene oxide

Infiltration

First change is in 1 part resin to 2 parts propylene oxide, allow to sit 3-4 hours or more

Second change is in 2 parts resin to 1 part propylene oxide, for 3-4 hours or more, 1 part propylene oxide to 2 parts resin overnight, rotating.

The next day, place samples in fresh resin at room temp; place samples in air tight containers and agitate or rotate samples slowly during infiltration. Then change into fresh resin at least 3-4 times, 2-4 hours per change

Embed samples in fresh resin in embedding mold, and position carefully.

Cure samples in 60°C oven for 3 days

Resin formula

Use pre-dessicated plastic beaker with gradations for easy measurements


45 ml Scipoxy 812 Other brands include Embed 812, Medcast, Epon
30 ml DDSA
25 ml NMA
Mix components well with wooden applicator
Add accelerator, 1.5 ml DMP-30
Mix resin thoroughly again
Place resin into dessicator and put under vacuum for 5-15 min to remove gasses from mixture before using

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