Quantitative analysis of the lobular distribution of S-phase in rat liver following dietary administration of di(2-ethylhexyl)phthalate.

A simple image-analysis method is described, whereby the distribution of hepatocytes that have entered S-phase, as distinguished by the incorporation of bromodeoxyuridine, can be related to the position of the central and portal veins of the hepatic lobule. Hepatocyte S-phase was induced in the livers of male and female F344 rats by administration of di(2-ethylhexyl)phthalate (DEHP) in the diet for 7 days at 2 dose levels, and these livers were used to develop the procedure. The distributions of the S-phase between control and DEHP-treated livers were compared using statistical techniques. The results showed notable differences in the distribution of S-phase between male and female rats as well as limited dose-related effects.