Table 2.

Possible outcomes and interpretations in liver sections from treated vs. control medaka.

Cell proliferation index	Apoptotic index	Pan- cytokeratin	Interpretations
−	−	−	Toxicant has no adverse effect on liver
+	+	−	Cells of liver independent of biliary passageways were targeted
− +	+ +	+ +	Toxicant targeted biliary epithelial cells as in acute toxicity.
+	−	+	Depending on duration (chronic) suggests remodeling of intrahepatic biliary passageways
−	−	+	Chronic toxicity has been repaired, biliary passageway architecture remains altered

Symbols:

⁻no difference detected between treatment and control

⁺significant difference detected between treatment and control

^*There are various outcomes not mentioned above. For example: whether the structure of the biliary cells shows alteration (swelling or shrinkage) after treatement; whether the nature of the tissue change constitutes hypertrophy or hyperplasia; and/or whether the space lined by the biliary cells shows alteration. Our intent here was to show how the method can be used to identify definitively biliary epithelia and to determine quantitative changes within the intrahepatic biliary cellular compartment with respect to cell proliferation and/or programmed cell death (apoptosis).