Effect of dietary fat on toad liver tumor induced by DMBA: ultrastructural studies.

Toads injected with 2 mg 7,12-dimethyl-benza(a)anthracene (DMBA)/toad, 3 times/week for 12 weeks induced liver tumors in 12 out of 50 cases. The electron micrograph of toad liver tumor showed disorganization of the rough endoplasmic reticulum which encircles or partially surrounds the mitochondria. Cristae mitochondrialis are rare in comparison with control. Enhancement of liver tumor incidences (29 out of 50 cases) by DMBA at the same dose level plus 2cc corn oil/toad, 3 times/week for 12 weeks was detected. Electronicrograph of this group showed the same criteria of malignancy as in the first group. No tumor incidences were detected in toads fed corn oil only. The electronmicrograph of liver cells showed a high increase in glycogen and lipid droplets.