Cytoplasmic Inclusions Containing 



Deoxyribonucleic Acid in the Neural Tube 



of Chick Embryos Exposed to Ionizing 



Radiation"^ 



Mary Elmore Saier and Donald Dincax 



University of Texas Medical Branch. 

 \ Galveston, Texas 



Introduction 



The identification of deoxyribonucleic acid ' DNA i with chromatin nor- 

 mally confines it to the nucleus of the cell. Nevertheless, reports of the 

 occurrence ot DXA in the cytoplasm are sufficiently numerous to suggest 

 that its presence there may be a phenomenon of wide distribution, even 

 thous:h the origin and destiny of such DNA may remain obscure. 



Perhaps not sufficiently appreciated is the large amount of cytoplasmic 

 DNA which makes its appearance in young embryos a few hours tollowing 

 moderate irradiation. The striking picture presented by the numerous Feul- 

 ^en positi\"e bodies in the neural tube of early chick embryos that had 

 received moderate doses of ionizing radiation prompted the present investi- 

 gation. This enlarges on a preliminary report t Sauer. 1957) dealing with 

 irradiated chick embryos. Since similar bodies ha\e a normal occurrence 

 Gliicksman. 1951: \on Sallmann ct al., 1957). their interpretation as an 

 injury response demands special caution. In the chick, the large number and 

 wide distribution ot these in irradiated embryos tar exceed any normal 

 appearance. 



Materials and Methods 



Chick embryos ranged from 2 to 4/2 days in incubation age at the time 

 of treatment, most being about 60 hours old. 



* Investigation supported in part by the U.S. Public Health Service. The authors 

 gratefully acknowledge the cooperation of Dr. \Iartin Schneider, who supervised the 

 .\-irradiation. and of Dr. Bruce E. Walker, who carried out the technique with the 

 tritium-labeled enibrvos. C. Drew Sanders gave technical assistance. 



