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Fixative tonicity for scannig electron microscopy of delicate chick embryos

1977; Wiley; Volume: 148; Issue: 1 Linguagem: Inglês

10.1002/aja.1001480109

1553-0795

Larry L. Litke, F. N. Low,

Tissue Engineering and Regenerative Medicine

Abstract Fresh pullet eggs (White Leghorn strain) were incubated from 19–26 hours. Blastoderms were fixed in ovo by selected fixatives of various tonicities, postfixed in 2% OsO 4 , dehydrated in acetone, critical‐point‐dried in liquid CO 2 , coated with palladium‐gold and observed in a Cambridge S4 scanning electron microscope. Shrunken cells with intracellular yolk granules embossed on the surface are produced by the strongly hypertonic Karnovsky's fixer (Final: 2010 mOsm). Embryos fixed with modified Karnovsky's fixer (Final: 373 mOsm) possess surfaces with irregular microappendages. Swollen cells with few microappendages are obsrved when embryos are fixed in a hypotonic environment (Final: 250 mOsm or less). Ideal fixatives preserve a relatively flat surface, with cells bordered by smooth surface microappendages. For adequate SEM fixation, fixative vehicle should be approximately isotanic for tissue, with aldehyde (2% or less) added to vehicle.