CHAPTER 4 - MICROSCOPIC OBSERVATIONS
METHYL CELLULOSE MOUNTING
(Source: R. Warga)
For a slightly less rigid mounting medium, use a lower concentration of agarose (0.1%) or 3% methyl cellulose.i.Methyl cellulose; (Sigma M-0387). Methyl cellulose is especially good for orienting young embryos (less than 10 h old).
1. Apply a drop of 3% methyl cellulose in embryo medium to a depression slide.
2. Suck an embryo up into a pasteur pipette and position it near the opening in the pipette.
3. Plunge the pipette into the methyl cellulose and gently expel the embryo with as little medium as possible. The medium around the embryo will be quickly absorbed into the methyl cellulose.
4. Use a fine loop of nylon fishing line to orient the embryo.
5. Place a drop of saline over the well to keep the preparation from drying out and getting too sticky.
6. To release the embryo, drop the entire slide into embryo medium for a few minutes. The methyl cellulose will absorb the medium and become very soft so that the embryo can be teased free with the nylon loop.
The methyl cellulose will swell and soften, and eventually the embryo will come free from the gel. If you are in a hurry, be patient for 15-30 minutes of softening before scraping the methyl cellulose away from the embryo with the nylon hair loop. Alternatively, embryos in methyl cellulose can soak overnight by leaving the slide in the dish containing embryo medium. However, if you do this, you should add antibiotics to the medium (final concentration 2% penicillin/streptomycin in embryo medium, see
The Zebrafish Book