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RP9 Terrestrial Ecotoxicology
(QUI-1116-004201) Embryonic estradiol exposure disrupts avian immune system development in Japanese quail.
Quinn, Jr., M1, McKernan, M2, Lavoie, E3, Hoffman, B3, Touart, L4, Ottinger, M3, 1 .S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD, USA2 USGS, Patuxent Wildlife Research Center, Laurel, MD, USA3 University of Maryland, Animal and Avian Sciences Department, College Park, MD, USA4 US Environmental Protection Agency, Washington, DC, USA
ABSTRACT- An embryo dose range finding protocol was developed to address dose range needs for the avian two generation test. This study evaluated sensitivity of immune endpoints in Japanese quail embryonically exposed to estradiol. Eggs were injected with vehicle control (sesame oil) or 0.5, 50 or 500 g/egg of estradiol (E2) in sesame oil at embryonic day 4. Quail were sampled on day of hatch and at maturity. Bursa of Fabricius and spleen weights were measured in hatchlings and adults. Bursal morphology was assessed in hatchlings, and bursal follicle size and numbers were measured. Bursa weights were decreased in a dose dependent, however adult bursas from the 500 g treatment group were larger than controls. Spleen mass remained unchanged in both hatchlings and adults. Morphological abnormalities in the bursa included thickening of the epithelial layers surrounding the bursal plicae that were more than three times as thick as controls. Although follicle number remained unchanged, follicle size was reduced in the 50 and 500 g hatchling treatment groups. This study identifies the bursa of Fabricius as a sensitive target of estradiol. The main role of the bursa is B cell maturation, therefore development of overall immunocompetence is dependent on the maturation of this lymphoid organ. The effects of estradiol on the bursa support the potential for disruption of immune system development by embryonic exposure to estrogenic endocrine disrupting chemicals. Funded by Battelle Labs in support of a U.S. EPA contract.
Key words: endocrine disrupting chemicals, estradiol, bursa of Fabricius, immune function
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