Glutaraldehyde fixation for electron microscopy of needle biopsies from human livers

A study including light- and electron microscopy of needle biopsies from normal and fatty human livers fixed by immersion into glutaraldehyde is presented. Four zones which can be detected by light microscopy of toluidine blue stained sections are found: zone 1, the outer one is presumably mechanically damaged. Zone 2 is usually considered to be the most well-preserved region, whereas zones 3 and 4 present increasing swelling of mitochondria, a progressive condensation of microbodies and an increasingly pronounced vesiculation of the smooth endoplasmic reticulum (SER). The alterations observed in zone 3 and 4 are of types which might simulate pathological changes. An increasing irregularity of the outline of the nuclei and a greater accumulation of chromatin along the nuclear membrane is also observed in these two zones. The perimembraneous cytoplasmic ground substance appears to be more dense and the intercellular spaces to be less distinct in the deeper zones in which the path of diffusion of the fixative is long. As regards the penetration into the tissue of glutaraldehyde, normal and steatotic livers were not found to differ. Fixation at 0 degrees C was found to be less effective than fixation at 22 degrees C.