Glutaraldehyde Fixatives for Preserving the Chick's Inner Ear

We preserved the inner ears of chicks in various concentrations of glutaraldehyde (2 to 3.5%) and cacodylate buffers (0.025 to 0.1 M). Buffer concentrations below 0.1 M caused osmotic damage that higher glutaraldehyde concentrations only partially counteracted. The combination of 3.5% glutaraldehyde and 0.1 M cacodylate buffer optimally preserved the different cell types and also eliminated problems of swelling and shrinkage. We further improved cellular preservation by immediately immersing the dissected specimen into chilled (4 degrees C), aerated fixative. The improved fixation greatly increased the retention of cytoplasmic ground substances, particularly in supporting cells and nerve terminals.