Effects of fixative composition on the ultrastructure of oral epithelium in guinea pigs.

Keratinizing epithelium from the hard palate of guinea pigs was used to investigate effects of variations in composition of fixative solutions on tissue preservation. With 2.5% glutaraldehyde as fixative, the volume of the basal intercellular spaces increased significantly when the buffer osmolality was increased by intervals of about 100 mOsm (0.05 M, 0.10 M and 0.15 M). The intercellular space volume appeared to be insensitive to differences in concentration of the fixative within the range of 2.5-5% glutaraldehyde. The preservation of mitochondria was improved by increasing the concentration of glutaraldehyde to 5% or by adding formaldehyde as a second fixative.