Lowicryl resin embedding

Carlemalm E, Villiger W, Hobot JA, Acetarin JD, Kellenberger E. Low temperature embedding with Lowicryl resins two new formulations and some applications. JMicrosc (Oxford) 1982b 140 55-63. 

For complete polymerization, it may be necessary to continne cnring the blocks by UV for up to 2 wk at either -20°C or room temperature. Temperature for infiltration and polymerization of Lowicryl K4M can be as low as -35°C. Samples that are embedded in resins that are polymerized by UV light (Lowicryl, LR White) should not be osmicated. The osmium may interfere with the polymerization by preventing the light from penetrating the samples. 

If embedding in a resin that is polymerized by UV light, such as Lowicryl and LR Gold, do not osmicate the samples. Any effect of the osmium on antigenicity can usually be eliminated by using sodium meia-periodate during etching to oxidize the unbound osmium (see step 7). 

Samples that are embedded m resins that are polymerized by UV light (Lowicryl, LR White) should not be osmicated. TTie osmium may interfere with the polymerization by preventing the light from penetrating the samples. 

A second approach to postembedding electron microscopic immunocytochemistry is the use of special aqueous resins, while these resins are still hydrophobic, they tolerate some aqueous material in the tissue. Examples of these resins are LR White or Lowicryl K4M. Another approach with aqueous embedding is to freeze tissue in buffer very rapidly, and to section with a cryo-ultramicrotome. Cryo-ultramicrotomy is a technique requiring considerable training and cannot be used by the novice. 

Hydroxyethyl acrylate (HEA) is contained in Lowicryl 4KM and KiiM resins. It caused contact dermatitis in workers embedding media for electron microscopy. It may also be contained in UV-cured nail gel used for photobonded sculptured nails. 

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