Journal of Microwave Power and Electromagnetic Energy (JMPEE)
TITLE	Temperature Gradients in the Microwave-Irradiated Egg: Implications for Avian Teratogenesis [PDF]
AUTHORS	R.L. Clarke and D. R. Justesen 1983 18 2 169-180
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Abstract Five experiments were performed on a total of 60 non-fertile eggs of Gallus gallus to determine the spatial character, persistence, and physical basis of thermal gradients after a 300-s exposure to the intense, multipath. 2.45-GHz yield of a multimode cavity (dose rates: ~ 80 to 120 mW/g). After irradiation of an intact egg that was first equilibrated to the ambient temperature, a 3-mm diameter Plexiglas rod, which was fitted with junctions of four microwire thermocouples at 10-mm intervals, was inserted to place the distal junction in the approximate center of the yolk, the most proximal junction in peripheral thin white. Temperatures measured immediately after irradiation revealed a highly reliable linear gradient of mean temperatures from central yolk to peripheral white (P < 0.001). The gradient was also highly persistent: Mean temperatures of central yolk exceeded those of outer thin white by more than 4°C 5 minutes after irradiation, and by more than 2°C 60 minutes afterward. In contrast, when an egg's contents were mixed before irradiation, the gradient was effectively eliminated. A previous report of athermally induced (field-specific) teratogenesis in chick embryos is placed under an interpretive cloud by the present findings: Terata emerged from eggs that were structurally intact during microwave irradiation, but estimates of maxima of embryonic temperatures were based on thermal measurements of non-fertile eggs the contents of which had been mixed by a thermal probe before irradiation.