| Abstrakt: |
Previous investigators have reported that exposure to a mixture of environmental contaminants, including polychlorinated biphenyls, results in morphologic asymmetry of the cerebral hemispheres in hatchling great blue herons (Ardea herodias) and have suggested that this asymmetry may be a useful biomarker for contamination. This study was made to determine whether exposure to PCB congeners 3,3',4,4'-tetrachlorobiphenyl (IUPAC #77) and 3,3',4,4',5-pentachlorobiphenyl (IUPAC #126) causes similar asymmetry in hatchling domestic chickens (Gallus domesticus). Eggs were injected at day 0 of incubation with either a high dose, low dose, or combination of each congener. At hatching, the chicks were perfused with 10% formalin-saline. The brains were removed, sectioned and stained with cresyl violet. Width and height measurements of each hemisphere were taken at eight locations, caudal to rostral, 400 microm apart starting at the level of the anterior commissure (CA) and ending at the lobus paraolfactorius (LPO). The absolute differences between measurements of the left and right sides were used to run a univariate split plot analysis of variance to determine if the amount of asymmetry present was associated with specific congeners or doses. Significant differences in asymmetry were found between noninjected control groups and vehicle-injected control groups (p
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