Uptake and tissue-specific distribution of selected polychlorinated biphenyls in developing chicken embryos

Fertilized chicken eggs were injected with high doses of individual polychlorinated biphenyl (PCB) congeners (0.5 mug of PCB 77, 9.8 mug of PCB 153, or 10.9 mug of PCB 180) before incubation to investigate the structure-specific uptake of these compounds by the embryo and their accumulation in brain and liver tissue. In accordance with earlier publications, a gradual uptake and accumulation of these compounds was observed during the last week of embryonic development. The PCB uptake and distribution to the specific tissues did not appear to be structure dependent. Wet-weight liver PCB concentrations (18, 266, and 278 ng/g at hatching for PCB 77, PCB 153, and PCB 180, respectively) were consistently two- to fourfold higher than carcass levels (7 ng/g of PCB 77, 117 ng/g of PCB 153, and 81 ng/g of PCB 180 at hatching). Whereas liver and carcass concentrations increased exponentially between day 13 of incubation and hatching, PCB levels in brain tissue remained unaltered (range, 0.6-1.0 ng/g of PCB 77 and 8-12 ng/g of PCB 153 and PCB 180 throughout the last week of incubation). Lipid analysis of the organs suggested that the lipid composition of brain may be an important factor explaining the low PCB accumulation in this tissue.