RADIATION IN PRENATAL DEVELOPMENT 



873 



abstract, Wilson and Karr (1950) mention that 200 r applied on day 9 will 

 kill all embryos, which would indicate that stage to be even more critical 

 for prenatal viability than day 10. 



While it is tempting to compare the results of Wilson and those of 

 Russell with a view to demonstrating a probable difference between rat 



Table 13-5. Viability after Prenatal Irradiation in the Rat: Comparison of 



the Results of Different Authors 



Senior 

 author 



Job, 1935 

 Wilson, 1950 

 Wilson, 1951 



Job, 1935 



Warkany, 1947 

 Warkany, 1947 

 Warkany, 1947 

 Job, 1935 



Warkany, 1947 

 Warkany, 1947 

 Warkany, 1947 

 Warkany, 1947 



Day 



irrad. 



9th- 15th 



9 



10 



8th-llth 



9 rf 

 10 

 11 

 12th-16th 



12 

 13 

 14 

 15 



Dose, r 



50 



1200 



Percentage of embryos or fetuses alive" 





 89(37)<> 100(2) 89(9) 12(8) 



0(10) 



Percentage of 9 9 with litter at term — average litter size' 



I I 



?%— 8.2 ?%— 7.4(237) 

 (41) 



50%— 4.9(44) 



79%— 3.0(45) 



92%— 4.9(54) 



?%— 11.0 ?%— 8.4(101) 

 (22) 



72 %— 5. 2(249) 



100%— 6.3(50) 



92%— 7.4(81) 



J 



75%— 7.5(45) 



" Observations recorded in this portion of the table were made as follows: in the work of Job el al., on day 18; in the experi- 

 ments of Wilson and Karr, on day 15 for 0-200 r, day 12 for 400 r. 



b Figures in parentheses indicate the number of young on which percentage alive or average litter size is based. 

 c Based only on litters brought to term. 

 d See text footnote 3. 



and mouse in susceptibility to prenatal killing, three further investiga- 

 tions, all on the rat, serve to show that even in the same species vastly 

 different results may be obtained, depending, perhaps, on genetic differ- 

 ences, details of method, or difficulties in early dosimetry. Job et al. 

 (1935) report 100 per cent resorption following exposure to only 95-200 r 

 (see Table 13-5). It must, however, be pointed out that females were 

 opened before irradiation to ascertain their pregnancy and, since no con- 



