Genotype identification of 10-day old Zucker rats by lipid content of inguinal fat pad

Surgical biopsies of the inguinal fat pad were performed on 35 fa/fa and 40 Fa/fa pups, aged 10 days, from eight litters. The lipid content of the pad, expressed as a percentage of the mean in each litter, allowed a 100 percent reliable prediction of the genotype. In three of the eight litters, we compared this method with that based on the frequency distribution of adipocyte size.