Those embryos where probably immersed in ethanol directly and probably their internal structure is not the best now. Your friend should determine the ethanol concentration they are now because, not matter how long they have been in ethanol, the embryos have to be completely dehydrate before processing and if the ethanol is 70% (as many museums use to) there is still some dehydraiton to do.
Find the ethanol conc., take the embryos out, wash them well in clean ethanol of the same concentration they are now, and complete the dehydration up to 100% ethanol.
I would not clear them in xylene because after so long in ethanol xylene will make them excessively brittle. I would try to clear the embryos in cedar wood oil until they are completely clear (transparent) and go to the bottom of the clearing container. After the dehydration, when your colleague places the embryos in the cedar wood oil, they will NOT sink, and you cannot permit them to hydrate again, so you cover the embryos (floating in the surface) with a piece of filter paper, and add 100% ethanol on top. This will prevent the embryos to hydrate. Once they sink (after clearing) place them in clean cedar wood oil for a few hours. Later "wash" them quickly with xylene and place them in the oven in melted paraffin (no more that 56║C) until infiltrate.Embed and section.
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