Mounting frozen embryos

From fixed embryos, cryoprotect in 30% sucrose/PBS overnight 4C
Before mounting, place embryos in 1:1 30% sucrose: OCT 1h on ice
Remove extraembryonic membranes using forceps
Count somites
Keep only posterior of embryo (cut off somewhere after embryo turn)
Stand embryo posterior up in 1 drop 30% sucrose: OCT on a clean penny
Leave penny on dry ice to freeze mounting media
Store at -80C until ready for sectioning