Abstract
This study was conducted to determine the effects of whole body gamma irradiation on the transport of thyroxine and iodide across the placenta of the albino rat of the Wistar strain. Pregnant females were irradiated on the 17th day of gestation with doses of 0, 500, 750, and 1000 rads from a Co⁶⁰ source, delivered at the rate of 600 rads per minute. On the 20th day of gestation the animals were injected with I¹³¹ labeled thyroxine or I¹³¹ labeled sodium iodide. Twelve hours later the animals were killed by ether anesthesia. The fetuses were homogenated in a Waring blender. Fetuses were homogenated intact within the extraembryonic membranes which included the placents and amniotic fluids, while additional fetuses were detached from the placenta and membranes and were homogenated separately. The remaining fetuses were fixed in a ten percent formalin solution and later weighed, crown-rump measurements were made, and representative fetuses were photographed. The uterus was homogenated following removal of all the fetuses. The amount of radioactivity present in an aliquot of each of the homogenates was determined by use of a scintillation detector. It was found that the transport of ionic iodide across the placenta was retarded following doses of 500 and 750 rads. The 1000 rad group showed higher readings than the 500 and 750 rad groups, but lower than those of the controls, which indicates a possible increase in the transport of iodine across the placenta. The rate of transfer of thyroxine across the placenta showed no significant difference between the dose levels used in this study. The weight of the fetuses whose dams had been irradiated was less than that of the controls, with no difference observed between radiation levels. Histological examination of the placentae showed no visible damage to the animals which had received 500 rads. Changes were observed in animals that had received 750 and 1000 rads. The basal plate contained many more degenerating cells accompanied by much more debris in this area. There was also a greater amount of hyalinization which accompanies the death of these cells.
Fougeron, Myron George (1967). The effects of whole body gamma irradiation on the transport of iodine across the placenta. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -169949.