Major developments in machine-vision light microscopy and in reagent c
hemistry have led to a renaissance and revolution in the use of the li
ght microscope in biology, biotechnology, and medicine. The potential
use of this technology in the field of toxicologic pathology is discus
sed. It is suggested that a combination of investigating living cells
and tissues and fixed samples using the new technologies will lead to
understanding mechanisms of toxicity. Examples of the use of the metho
ds in basic cell biology and medicine are presented.